In Memoriam
In Memoriam
In Memoriam: Niels Peder Kristensen (1943–2014)
expand article infoThomas J. Simonsen, Ole Karsholt§, Malcolm Scoble
‡ Natural History Museum, London, United Kingdom
§ The Natural History Museum of Denmark, Copenhagen, Denmark
Open Access

Niels Peder Kristensen, Honorary Member and former president of SEL, passed away on Saturday December 6th 2014 in Copenhagen. While his death was not unexpected, its timing came earlier than we had thought or hoped. His loss is felt widely and intensely.

Figure 1. 

Niels Peder Kristensen, March 2nd 1943 – December 6th 2014 (photo: Birgit Nielsen).

Born on March 2nd 1943, Niels was the second child of Thorkil and Ellen Christine Kristensen (nee Nielsen). His father was an academic, politician and thinker who served as Minster of Finance in two different government cabinets, and later as General Secretary of the OECD. Growing up in such an environment undoubtedly had a profound influence on Niels’ own world view, one which was powerfully international in its expression, yet retaining a strong interest and deep concern for Danish issues – local and national.

Niels developed an interest in entomology and lepidopterology in particular at an early age, and once told TJS about the first time, when eight years old, he visited the Entomology Department at the Zoological Museum in Copenhagen (ZMUC) ‘clutching his father’s hand’. After completing high school at Birkerød Statsskole in 1961, Niels enrolled as a biology student at the University of Copenhagen, and quickly became a regular visitor to the Entomology Department of the Museum, where he had already started as a volunteer during his last years at high school. In 1965, while still a student, he published his first paper, which was on the faunistics of Danish cicadas. From the very start of his scientific career, one of Niels’ abiding interests was the evolution (particularly evolutionary morphology) of primitive Lepidoptera. Indeed, the work for his Mag. Scient. degree was on the comparative morphology of the primitive glossatan family, Eriocraniidae. During this study, Niels spent the academic year 1966–67 at the University of Bristol, working with the eminent and extremely knowledgeable British entomologist Howard E. Hinton, who was at that time pioneering the use of scanning electron microscopy in entomology. It was while working with Hinton that Niels came to appreciate the value of SEM in comparative morphology. Through it, he made the surprising discovery (published in 1970) that the most primitive Lepidoptera have flat, solid wing scales (i.e. lacking an internal lumen), a condition contrasting strongly with the hollow wing scales generally found in Lepidoptera.

After obtaining his Mag. Scient. degree in 1968, Niels was offered a tenure-track position at the ZMUC as Amanuensis (Assistant Professor). He was promoted to Associate Professor in 1972 and appointed as Full Professor of Entomology in 1995. In 1970, Niels visited one of Europe’s foremost comparative invertebrate morphologists, Jean Chaudonneret, at the Université de Dijon where he enhanced considerably his skills in insect histology and semi-thin sectioning. Working with Hinton, Chaudonneret and Karl G. Wingstrand, the professor of comparative morphology at the University of Copenhagen, unquestionably had a profound influence on Niels’ development as a scientist. He often referred to the effect these three mentors had on his career. Niels was also deeply interested in the analytical methods used in evolutionary research. Together with fellow entomologist Nils Møller Andersen and the palaeontologist Niels Bonde, he was a pioneer in Denmark, and more widely in Scandinavia, of Hennig’s phylogenetic systematics, and his cladistic analyses of the higher-level relationships of butterflies in 1976 remained the standard work on the subject until the study by de Jong et al. (1996) 20 years later.

From the very start of his career, Niels was deeply interested in the morphology and phylogeny of the higher insects. In 1975 he published (Z. zool. Syst. Evolut.-forsch. 13, pp. 1–44) one of his most influential papers: “The phylogeny of hexapod ‘orders’. A critical review of recent accounts”. Thirty years later, Grimaldi and Engel (2005, p. 144) referred to this work as “perhaps the single most important paper in systematic entomology”. This publication formed the basis of his five updated reviews of the subject. The last of these was published in Eur. J. Ent. in 1999, while perhaps the most notable of them is the 1991 text-book chapter “Phylogeny of extant hexapods” in “The Insects of Australia”, which should be mandatory reading for all students of systematic entomology. Over the years Niels authored or co-authored a number of papers on higher Hexapod relationships especially on the lower Hexapod orders, Trichoptera, the enigmatic New Zealand mecopteran family Nannochoristidae, Neuroptera, and of course Mantophasmatodea—the first new insect order to be described for 90 years, the description of which he co-authored in 2004.

It was, however, the Lepidoptera that remained Niels’ main interest, and the majority of his publications are on that order. They range in scope from nomenclatural and faunistic notes to higher-level phylogenetics and to the exceptionally detailed, comparative morphological studies of primitive Lepidoptera. More than anything else, these exquisite studies became his professional hallmark. His early enthusiasm for scanning electron microscopy and histology were combined with transmission electron microscopy and became methodological cornerstones in his work throughout his working life. Much of his productivity, particularly in the first half of his career, led to highly detailed studies of little-understood structures and organ systems of primitive Lepidoptera, including overall head and neck anatomy, mouthpart morphology, anatomy of the alimentary canal, structure of the trachaea system, comparative morphology and anatomy of male and female genitalia, and wing scales and vestiture. Niels’ work on primitive Lepidoptera morphology and anatomy was always embedded in the context of higher Lepidoptera evolution, and his ultimate goal was to establish the early evolutionary patterns within the order, thereby creating a sound basis for further studies higher up the lepidopteran tree. In 1978 and 1979 he also described two new families of primitive Lepidoptera, the basal hepialoid family Neotheoridae and the non-ditrysian family Heterobathmiidae (the latter in collaboration with the late Ebbe S. Nielsen). His work on primitive Lepidoptera phylogeny and comparative morphology culminated in his Dr Scient. dissertation “Studies on the morphology and systematics of primitive Lepidoptera” published in Steenstrupia in 1984. Until the modifications introduced by the very recent advent of phylogenomic studies and especially the surprising discovery of a new primitive moth family from Australia, this remained the standard work on the evolution of the homoneurous Lepidoptera.

In the early 1990s Niels was appointed the editor-in-chief of the two Lepidoptera volumes of the Handbook of Zoology. This immense undertaking was to dominate his professional life for the following decade. The two volumes, which were published in 1998 and 2003, defined the latter part of his career as much as his work on higher Hexapod phylogeny and comparative Lepidoptera morphology had shaped his early and mid career, although he continued his work on these topics until illness forced him to stop just weeks before his death. Niels had anticipated writing or co-authoring a substantive part of the first volume. He did not, however, expect to have made a similar input to the second volume, which was on morphology and physiology. Having to do so resulted in a much greater effort on his part than he had intended: moreover, it required him to write about subjects on which he did not consider himself an expert. The result, nevertheless, stands as a landmark publication and a tribute to Niels’ capacity and breadth of knowledge. The Handbook would have been more than enough of a mega-project for most of us, so it is remarkable that Niels also spent much time and effort during his last years editing a book on the insects of Greenland instead of completing some of his own research projects. While he certainly believed in the value of the Greenland work, his resolve was propelled by that innate sense of responsibility and conscientiousness that were so evident in his personal makeup.

After the mammoth task of completing the Handbook, Niels returned to his work on primitive Lepidoptera — at least as much as his administrative duties permitted. At the time of his death, he was involved in long-term studies of several groups: Micropterigidae with G. W. Gibbs and D. L. Lees; Mnesarchaeidae with G. W. Gibbs; Hepialoidea with TJS. A phylogenomic study of the non-ditrysian lineages (part of the LepTree project), of which he was a senior co-author, was submitted just weeks after his death (and was dedicated to him). But his most significant contribution in the last stage of his career was the discovery and description of an extraordinary homoneuran family from Kangaroo Island, Australia (the so-called Kangaroo Island Moth, or KIM) and its significance for modifying our understanding of early Lepidoptera evolution. The paper was, to his great pleasure, accepted for publication before his death.

Figure 2. 

Niels studying his beloved homoneuran Lepidoptera (photo: TJS).

Besides being a leading research scientist, Niels was a highly engaging and inspiring teacher and supervisor. Early in his career, he wrote, in Danish, a detailed yet concise compendium of systematic entomology (“Systematisk Entomologi” 1974), which for years was the standard textbook on the subject at the University of Copenhagen. For over two decades he was a driving force behind an advanced course in systematic entomology and insect morphology, which was taught biennially at the University. Niels’ lectures displayed not only the depth of his learning, but were rich in subtle humour, a quality of which he was a master. TJS recalls a particular entomology lecture (in 1996) in which Niels was explaining the morphology of the thorax, including flight mechanisms. To ensure that the students understood the complex ways in which insects move their wings to minimize drag, he demonstrated by lying face down on a table, still clad in jacket and tie and with his feet sticking out, waiving his arms in the air! While this performance was not characteristic of most university professors, it worked — TJS resolved there and then to do his graduate studies under Niels’ supervision.

Throughout his career, Niels supervised several Masters and PhD students and postdoctoral fellows. He took a deep interest in their well-being, both professional and personal, and derived immense pleasure from their subsequent successes while keeping in close contact with them after they graduated. (After graduating and moving away from Copenhagen, TJS spent numerous hours on the phone with Niels discussing his own work, Niels’ work, the world in general and entomology in particular.) It was therefore also with great sadness and regret that he found himself writing obituaries for two of his most talented PhD students, the coleopterist Michael Hansen and the lepidopterist Ebbe S. Nielsen, both of whom died prematurely in the year 2000. Niels considered the more sociological aspects of entomology and lepidopterology to be integral parts of the (informal) training of a student. TJS recalls numerous meetings with Niels, intended to be brief, but often extending to a couple of hours, and invariably covering a wide range of aspects such as the history of science, the works (present and past) of other entomologists, anecdotes, amateur entomology, entomology and society. One of Niels’ great qualities as a supervisor was that hallmark of all top supervisors — he had an intuitive understanding of the level and extent of supervision needed to fit the individual student, endeavouring always to bring out the best in him or her.

Niels started collecting butterflies and moths as a schoolboy, and although he never built up a large collection, this activity influenced his choice to become a biologist and a specialist in Lepidoptera. At that time there was no tradition for lepidopterology at the ZMUC, and Niels was the first academically trained lepidopterist at the museum — despite being advised by the head of the entomology department at that time, S. L. Tuxen, to find a more scientific group! Later he often defended collecting Lepidoptera, arguing that is an important way to get young people interested in entomology.

Niels appreciated deeply (serious) amateur lepidopterists, being well aware that major parts of the Lepidoptera collections in larger museums had been collected by them. He valued their efforts, spoke positively and warmly about them and did much to help them, for example through his work for societies with large amateur memberships, by advising on scientific matters and in providing help to get collecting permits.

While Niels enjoyed experiencing Lepidoptera and other insects in nature, and he would often run a mercury vapour light at his summer cottage, he was not primarily a field worker. He felt, and indeed demonstrated, that he could serve the study of Lepidoptera best by focusing his exceptional skills on the study of key taxa at the museum bench.

Besides his research and teaching, Niels shouldered a substantial administrative burden at the ZMUC, at which he spent his entire career. This included several stints as Chair or Deputy Chair of the Entomology Department, two periods as Deputy Director of the museum, and three years as Director. He was also Head of Zoology at the newly designated Natural History Museum of Denmark from 2004–2006. Although his heart remained in his research, he carried out these time-consuming administrative responsibilities conscientiously and with a great sense of love and concern for the museum.

Throughout his career, Niels was deeply involved in entomological and lepidopterological societies. He was President of the Danish Entomological Society from 1989 to 1999, Council member of the International Congress of Entomology from 1988 to 2004 (Deputy Chair 2000–2004), and of course President of the SEL from 1998 to 2007, and Chair of the SEL congress in Korsør, Denmark in 2002. One of Niels’ long-standing ambitions was to hold a joint European-North American Lepidoptera Congress. Although this did not take place during his own tenure as President, he was very pleased to see the first joint meeting of the Lepidopterists’ Society and SEL in Denver, Colorado in 2012 (even if he could not attend the meeting himself).

During his career, Niels received many honours and awards, a testimony to his achievements and pre-eminence in his field. He was a member of the Danish Academy of Natural Sciences, a member of the Royal Danish Academy of Sciences and Letters, a corresponding member of the Finnish Entomological Society, an honorary ‘Foreign member’ of the Linnean Society of London (1998), an honorary member of Sociedad Hispano-Luso-Americana de Lepidopterologia (SHILAP), an honorary member of the Danish Entomological Society, an honorary research fellow at the Natural History Museum, London, an honorary member of Gesellschaft für Biologische Systematik, an honorary member of Societas Europaea Lepidopterologica, an honorary fellow of the Royal Entomological Society, and an honorary member of the Russian Entomological Society. In 1988 he was awarded the ‘Karl Jordan Medal’ (Lepidopterists’ Society) for “outstanding original research in lepidopterology”, in 1999 he received the Joachim Jungius-Medaille (J.J.Gesellschaft der Wissenschaften, Hamburg) for “herausragender Leistungen in Wissenschaft und Forschung”, and in 2014 shortly before his death he gained the 2014 Linnean Medal (Zoology).

Niels cared deeply about the future of European entomology and lepidopterology and was dismayed by the progressive decline of staff numbers and funds at several major research institutions (including his own in Denmark). He believed firmly in the need for basic research, and that in publicly funded institutions such as museums it should be possible for researchers to focus on academically interesting questions that do not necessarily have immediately obvious economic, social or medical benefits.

Unsurprisingly, Niels’ standing, awareness and understanding of wider socio-political issues in science led to him being asked to act as Director of the ZMUC. While he had an interest in university politics and administration, his real love was for his research, but he accepted the position (doing two terms of service) partly from a sense of duty, and partly because he felt that the position should be held by an acknowledged researcher rather than a mandarin. Having high ethical standards, Niels rarely sought the easiest solution to any problem, but rather the one that he thought to be right. He was a conscientious leader, made great efforts to keep abreast of relevant matters and always made time for his colleagues, whatever their level in the organization. He undoubtedly suffered during his extended directorship, both as a result of these personal qualities and through the loss of most of his time for research. Alas, he had to endure more frustration due to seemingly endless cuts to the museum’s funds. But when the Ministry of Education and Research ordered cuts of several positions at the museum, he felt he could no longer accept the responsibility for running the institution and stepped down in protest.

Niels was critical of the plans for a new natural history museum in Copenhagen, which would have resulted in newer but reduced facilities. He was particularly disturbed about the idea of demolishing the ZMUC building, which had been purpose built and which he considered to be still fit for purpose. During his later years he spoke and wrote against the idea, and was disappointed that the management of the Natural History Museum of Denmark, and many of his colleagues, did not agree with him. He also expressed concern about the appointment at the museum of scientists with little experience of collections-based research.

At the time of his death, Niels had settled into a productive retirement: relieved of administrative responsibilities, it was a phase of his life that he was enjoying thoroughly. So it is heart-breaking that he missed the prolonged and active retirement he would have found so fulfilling. Moreover, it leaves the scientific community bereft of the many works that would surely have been produced by him. The entomological world has become a much poorer place without Niels’ profound knowledge and insight, his generosity of spirit, his conscientiousness and his quiet humour. For all these qualities he is and will continue to be missed deeply. He was also a loving family man and our deepest condolences are extended to his wife Else and their daughters.

HAVAMAL (Our translation)

Livestock die

Kinsman dies

We all die just the same

Only one thing I know which never dies

The judgment of a dead man’s life.

HAVAMAL (Danish)

Fæ dør

Frænde dør

Dør selv på samme vis

Kun et ved jeg som aldrig dør

Dommen over død mands liv


We wish to thank Lars Vilhelmsen, Natural History Museum of Denmark for sharing biographical data he had collected. We thank Birgit Nielsen, Frederiksværk, Denmark for permission to use the portrait photo of Niels P. Kristensen.


  • de Jong R, Vane-Wright RI, Ackery PR (1996) The higher classification of butterflies (Lepidoptera): problems and prospects. Entomologica scandinavica 27: 65–101. doi: 10.1163/187631296X00205
  • Grimaldi D, Engel MS (2005) Evolution of the Insects. Cambridge University Press, Cambridge, UK, 755 pp.

Niels Peder Kristensen, publications

  • 156. Karsholt O, Kristensen NP, Simonsen TJ, Ahola M (in press) Lepidoptera (moths and butterflies). 51 pp. In Böcher J, Kristensen NP, Pape T, Vilhelmsen L (Eds). The Greenland entomofauna. An identification manual of insects, spiders and their allies. E. J. Brill, Leiden.
  • 155. Kristensen NP, Hilton DJ, Kallies A, Milla L, Rota J, Wahlberg N, Wilcox SA, Glatz RV, Young DA, Cocking G, Edwards ED, Gibbs GW, Halsey M (2015) A new extant family of primitive moths from Kangaroo Island, Australia, and its significance for understanding early Lepidoptera evolution. Systematic Entomology 40: 5–16. doi: 10.1111/syen.12115
  • 154. Kristensen NP, Rota J, Fischer S (2014) Notable plesiomorphies and notable specializations: head structure of the primitive “tongue moth” Acanthopteroctetes unifascia (Lepidoptera: Acanthopteroctetidae). Journal of Morphology 275: 153–172. doi: 10.1002/jmor.20205
  • 153. Kristensen NP (2013) Intraspecific variability in gross design of moth brains: A caveat concerning expectedly ‘good’ characters’ in systematic entomology (Insecta: Lepidoptera). Zoologischer Anzeiger 253: 112–113. doi: 10.1016/j.jcz.2013.09.002
  • 151. Hünefeld F, Kristensen NP (2012) The female postabdomen and genitalia of the basal moth family Heterobathmiidae (Insecta: Lepidoptera): Structure and phylogenetic significance. Arthropod Structure & Development 41: 395–407. doi: 10.1016/j.asd.2012.05.001
  • 150. Beutel RG, Kristensen NP (2012) Morphology and insect systematics in the era of phylogenomics. Arthropod Structure & Development 41: 303–305. doi: 10.1016/j.asd.2012.05.003
  • 149. Hünefeld F. Kristensen NP (2012) Two new heterobathmiid moth species with distinctive female genital configurations (Lepidoptera: Heterobathmiidae). Zootaxa 3281: 61–68.
  • 148. Kristensen NP (2012) Molecular phylogenies, morphological homologies and the evolution of moth ‘ears’. Systematic Entomology 37: 237–239. doi: 10.1111/j.1365-3113.2012.00619.x
  • 147. Gibbs GW, Kristensen NP (2011) Agrionympha, the long-known South African jaw moths: a revision with descriptions of new species (Lepidoptera, Micropterigidae). Zootaxa 2764: 1–21.
  • 146. Djernæs M, Kristensen NP (2011) Derived morphology in a basal moth: The uniquely specialized sternum V glands of Agathiphaga. Arthropod Structure & Development 40: 559–569. doi: 10.1016/j.asd.2011.06.001
  • 145. Rota J, Kristensen NP (2011) Notes on taxonomic history, thoraco-abdominal articulation, and current placement of Millieriidae (Insecta: Lepidoptera). Zootaxa 3032: 65–68.
  • 144. van Nieukerken E, Kaila L, Kitching IJ, Kristensen NP, Lees, DC, Minet J, Mitter C, Mutanen M, Regier JC, Simonsen TJ, Wahlberg N, Yen S-H, Zahiri R, et al. (38 additional authors) (2011) Order Lepidoptera. In: Zhang Z-Q (Ed.) Animal biodiversity: An outline of higher-level classification and survey of taxonomic richness. Zootaxa 3148: 212–221.
  • 143. Kristensen NP (2011) Michael Fibiger 29. juni 1945 – 16. februar 2011. Entomologiske Meddelelser 79: 153–165.
  • 142. Hünefeld F, Kristensen NP (2010) The female postabdomen and internal genitalia of the basal moth genus Agathiphaga (Insecta: Lepidoptera: Agathiphagidae): Morphology and phylogenetic implications. Zoological Journal of the Linnean Society 159: 905–920. doi: 10.1111/j.1096-3642.2009.00590.x
  • 141. Kristensen NP, Gaedike R (2010) Extraordinary moths and an extraordinary moth researcher: An essay review of G. S. Robinson’s Biology, distribution and diversity of tineid moths. Nota Lepidopterologica 33: 3–8.
  • 140. Lees DC, Rougerie R, Zeller-Lukaschort C, Kristensen NP (2010) DNA mini-barcodes in taxonomic assignment: a morphologically unique new homoneurous moth clade from the Indian Himalayas described in Micropterix (Lepidoptera, Micropterigidae). Zoologica Scripta 39: 642–661. doi: 10.1111/j.1463-6409.2010.00447.x
  • 139. Kristensen N P, Nielsen PS (2010) Et Hoffmeyer-manuscript om vore ’stribede’ køllesværmere. Lepidoptera 9: 289–307.
  • 138. Beutel RG, Kristensen NP, Pohl H (2009) Resolving insect phylogeny: The significance of cephalic structures of the Nannomecoptera in understanding endopterygote relationships. Arthropod Structure and Devopment 38: 427–460. doi: 10.1016/j.asd.2009.05.002
  • 137. Kaaber S, Kristensen NP, Simonsen TJ (2009) Sexual dimorphism and geographical male polymorphism in the ghost moth Hepialus humuli (Lepidoptera: Hepialidae): Scale ultrastructure and evolutionary aspects. European Journal of Entomology 106: 303–313. doi: 10.14411/eje.2009.036
  • 136. Béthoux O, Kristensen NP, Engel M (2008) Hennigian phylogenetic systematics and the ‘groundplan’ vs. ‘post-groundplan’ approaches: A Reply to Kukalová-Peck. Evolutionary Biology 35: 317–323. doi: 10.1007/s11692-008-9035-6
  • 135. Kristensen NP (2008) Natsværmeren ‘humleæder’, dens flyveaktivitet, vingeskæl-struktur og variation I Nordeuropa. Dyr i Natur og Museum 2008/2: 22–25.
  • 134. Kristensen NP (2008) Early Lepidoptera evolution. Gesellschaft für Biologische Systematik Newsletter 20: 50–55.
  • 133. Kristensen NP, Scoble MJ, Karsholt O (2007) Lepidoptera phylogeny and systematics: the state of inventorying moth and butterfly diversity. Zootaxa 1668: 699–747.
  • 132. Kristensen NP (2007) Nils Møller Andersen. Dansk Naturhistorisk Forening Årsskrift 16/17: 50–51.
  • 131. Kristensen NP (2007) Leif Lyneborg – 3. januar 1932 – 10. september 2006. Dansk Naturhistorisk Forenings Årsskrift 16/17: 68–75.
  • 130. Faucheux MJ, Kristensen NP, Yen S-H (2006) The antennae of neopseustid moths: Morphology and phylogenetic implications, with special reference to the sensilla (Insecta, Lepidoptera, Neopseustidae). Zoologischer Anzeiger 245: 131–142. doi: 10.1016/j.jcz.2006.05.004
  • 129. Kristensen NP (2006) Nils Møller Andersen 21. november 1940 – 12. maj 2004. Det Kongelige danske videnskabernes Selskab. Oversigt over Selskabets Virksomhed 2004–05: 217–224.
  • 127. Krenn HW, Kristensen NP (2004) Evolution of proboscis musculature in Lepidoptera. European Journal of Entomology 101: 565–575. doi: 10.14411/eje.2004.080
  • 126. Kristensen NP (2004) Om indsamling og udskillelse. Nogle naturhistoriske perspektiver. Danske Museer 17/5: 20–21.
  • 125. Kristensen NP (2004) Paul Johannes Holst-Christensen. Dansk Naturhistorisk Forening Årsskrift 14: 86–89.
  • 124. Kristensen NP (2003) Resolving the basal phylogeny of Lepidoptera: morphological evidence. Entomologische Abhandlungen 61: 167–169.
  • 123. Kristensen NP (2003) Reproductive organs. Pp. 427–447 in N.P.Kristensen (Ed.) Lepidoptera: Moths and butterflies 2. Handbuch der Zoologie/Handbook of Zoology IV/36: Walter de Gruyter, Berlin & New York.
  • 122. Akai H, Hakim RS, Kristensen NP (2003) Labial glands, silk and saliva. Pp. 377–388 in N.P.Kristensen (ed.) Lepidoptera: Moths and butterflies 2. Handbuch der Zoologie/Handbook of Zoology IV/36: Walter de Gruyter, Berlin & New York.
  • 121. Warrant E, Kelber A, Kristensen NP (2003) Eyes and vision. Pp. 325–359 in N.P.Kristensen (ed.) Lepidoptera: Moths and butterflies 2. Handbuch der Zoologie/Handbook of Zoology IV/36: Walter de Gruyter, Berlin & New York.
  • 120. Barbehenn RV, Kristensen NP (2003) Digestive and excretory system. Pp. 165–187 in N.P.Kristensen (ed.) Lepidoptera: Moths and butterflies 2. Handbuch der Zoologie/Handbook of Zoology IV/36: Walter de Gruyter, Berlin & New York.
  • 119. Hasenfuss I, Kristensen NP (2003) Skeleton and muscles: immatures. Pp. 133–164 in N.P.Kristensen (ed.) Lepidoptera: Moths and butterflies 2. Handbuch der Zoologie/Handbook of Zoology IV/36: Walter de Gruyter, Berlin & New York.
  • 118. Kristensen NP (2003) Skeleton and muscles: adults. Pp. 39–131 in N.P.Kristensen (ed.) Lepidoptera: Moths and butterflies 2. Handbuch der Zoologie/Handbook of Zoology IV/36: Walter de Gruyter, Berlin & New York.
  • 117. Kristensen NP, Simonsen TJ (2003) ‘Hairs’ and scales. Pp. 9–22 in N.P.Kristensen (ed.) Lepidoptera: Moths and butterflies 2. Handbuch der Zoologie/Handbook of Zoology IV/36: Walter de Gruyter, Berlin & New York.
  • 116. Chauvin G, Kristensen NP (2003) Integument. Pp. 1–8 in N.P.Kristensen (ed.) Lepidoptera: Moths and butterflies 2. Handbuch der Zoologie/Handbook of Zoology IV/36: Walter de Gruyter, Berlin & New York.
  • 115. Kristensen NP, Simonsen TJ (2003) Scale length/wing length correlation in Lepidoptera. Journal of Natural History 37: 673–679. doi: 10.1080/00222930110096735
  • 114. Karsholt O, Kristensen NP (2003) Plesiozela, gen. nov. from temperate South America: apparent sister-group of the previously known Heliozelidae (Lepidoptera: Incurvarioidea: Heliozelidae). Invertebrate Systematics 17: 39–46. doi: 10.1071/IS02047
  • 113. Karsholt O, Kristensen NP (2003) Kastaniemøllet: et kønt nyt skadedyr i Danmark. Dyr i Natur og Museum 2003/1: 9–11.
  • 112. Kristensen NP (2002) Mantophasmatodea: en nyopdaget orden af nulevende insekter. Dyr i Natur og Museum 2002/2: 24–27.
  • 111. Klass K-D, Zompro O, Kristensen NP, Adis J (2002) Mantophasmatodea: a new insect order with extant members in the Afrotropics. Science 206: 1456–1459. doi: 10.1126/science.1069397
  • 110. Kristensen NP (2002) Ebbe Schmidt Nielsen. Dansk Naturhistorisk Forening Årsskrift 12: 58–60.
  • 109. Kristensen NP (1994–2002) Contributions to ‘Danmarks Nationalleksikon’/’Den Store Danske Encyklopædi’ (vols 1–20, Gyldendal, Copenhagen), including ‘Dagsommerfugle’ [butterflies], ‘Insekter’ [insects], ‘Leddyr’ [arthropods], ‘Sommerfugle’ [Lepidoptera], ‘Urinsekter’ [apterygotes] and numerous shorter (< 50 lines) articles on zoological (mostly entomological) subjects, including biographies of zoologists.
  • 108. Simonsen TJ, Kristensen NP (2001) Agathiphaga wing vestiture revisited: evidence for complex early evolution of lepidopteran scales (Lepidoptera: Agathiphagidae). Insect Systematics and Evolution 32: 169–175. doi: 10.1163/187631201X00128
  • 107. Klass K-D, Kristensen NP (2001) The ground plan and affinities of hexapods: recent progress and open problems. Annales de la Société Entomologique de France (N. S.) 37: 265–298.
  • 106. Kristensen NP (2001) Ebbe Schmidt Nielsen 7 June 1950 - 6 March 2001. Nota Lepidopterologica 24/3: 3–9.
  • 105. Kristensen NP (2001) Henning Anthon. Entomologiske Meddelelser 69: 65–68.
  • 104. Kristensen NP (2001) Michael Hansen. Dansk Naturhistorisk Forening Årsskrift 11: 67–69.
  • 103. Krenn HW, Kristensen NP (2000) Early evolution of the proboscis of Lepidoptera (Insecta): external morphology of the galea in basal glossatan moth lineages, with remarks on the origin of the pilifers. Zoologisher Anzeiger 239: 179–196.
  • 102. Kristensen NP (1999) Phylogeny of endopterygote insects, the most successful lineage of living organisms. European Journal of Entomology 96: 237–253.
  • 101. Dugdale JS, Kristensen NP, Robinson, GS, Scoble MJ (1998) The smaller microlepidoptera-grade superfamilies. Pp. 217–232 in N.P.Kristensen (ed.) Lepidoptera: Moths and butterflies 1. Handbuch der Zoologie/Handbook of Zoology IV/35(1999): 51–63. Walter de Gruyter, Berlin & New York.
  • 100. Edwards ED, Gentili P, Horak M, Kristensen NP, Nielsen ES (1998) The Cossoidea and Sesioidea. Pp. 181–197 in N.P.Kristensen (ed.) Lepidoptera: Moths and butterflies 1. Handbuch der Zoologie/Handbook of Zoology IV/35: (1999) 51–63. Walter de Gruyter, Berlin & New York.
  • 99. Dugdale JS, Kristensen NP, Robinson GS, Scoble MJ (1998) The Yponomeutoidea. Pp. 119–130 in N.P.Kristensen (ed.) Lepidoptera: Moths and butterflies 1. Handbuch der Zoologie/Handbook of Zoology IV/35(1999): 51–63. Walter de Gruyter, Berlin & New York.
  • 98. Kristensen NP (1998) The homoneurous Glossata. Pp. 51–63 in N.P.Kristensen (Ed.) Lepidoptera: Moths and butterflies 1. Handbuch der Zoologie/Handbook of Zoology IV/35(1999): 51–63. Walter de Gruyter, Berlin & New York.
  • 97. Kristensen NP (1998) The non-glossatan moths. Pp. 41–49 in N.P.Kristensen (Ed.) Lepidoptera: Moths and butterflies 1. Handbuch der Zoologie/Handbook of Zoology IV/35: 51–63(1999). Walter de Gruyter, Berlin & New York.
  • 96. Carter D, Kristensen NP (1998) Classification and keys to higher taxa. Pp. 27–40 in N.P.Kristensen (ed.) Lepidoptera: Moths and butterflies 1. Handbuch der Zoologie/Handbook of Zoology IV/35(1999): 51–63. Walter de Gruyter, Berlin & New York.
  • 95. Kristensen NP, Skalski A (1998) Palaeontology and phylogeny. Pp. 7–25 in N.P.Kristensen (ed.) Lepidoptera: Moths and butterflies 1. Handbuch der Zoologie/Handbook of Zoology IV/35(1999): 51–63. Walter de Gruyter, Berlin & New York.
  • 94. Kristensen NP (1998) Historical Introduction. Pp. 1–5 in N.P.Kristensen (ed.) Lepidoptera: Moths and butterflies 1. Handbuch der Zoologie/Handbook of Zoology IV/35(1999): 51–63. Walter de Gruyter, Berlin & New York.
  • 93. Kristensen NP, Nielsen E S (1999). Heterobathmia valvifer n.sp.: A moth with large apparent “ovipositor valves” (Lepidoptera, Heterobathmiidae). Steenstrupia 24(1998): 141–156.
  • 92. Kristensen NP (1997) Early evolution of the Lepidoptera + Trichoptera lineage: phylogeny and the ecological scenario. Mémoires du Muséum National d´histoire Naturelle 173: 253–271. [Japanese translation, with minor differences: pp. 182–200 in T. Yasuda (Ed.) (1988): Biology of Microlepidoptera]
  • 91. Kristensen NP (1997) The ground plan and basal diversification of the hexapods. Pp. 281–293 in Fortey, R. A. & Thomas, R. H. (eds), Arthropod Relationships, Chapman & Hall, London.
  • 90. Kristensen NP (1997) Japetus Steenstrup – 100 år efter. Dyr i Natur og Museum 1997/2: 21–25.
  • 89. Kristensen NP (1997) Myreløver i Danmark. Dyr i Natur og Museum 1997/1: 24–27.
  • 88. Nielsen ES, Kristensen NP (1996) The Australian moth family Lophocoronidae and the basal phylogeny of the Lepidoptera–Glossata. Invertebrate Taxonomy 10: 1199–1302. doi: 10.1071/IT9961199
  • 87. Davis DR, Karsholt O, Kristensen NP, Nielsen ES (1995) A revision of the genus Ogygioses (Lepidoptera: Palaeosetidae). InvertebrateTaxonomy 9: 1231–1263. doi: 10.1071/IT9951231
  • 86. Kristensen NP (1995) Forty years’ insect phylogenetic systematics. Hennig’s “Kritische Bemerkungen...” and subsequent developments. Zoologische Beiträge (N. F.) 36: 83–124.
  • 85. Kristensen NP (1995) Sydbøgemøllene. Dyr i Natur og Museum 1995/1: 30–31.
  • 84. Kristensen NP (1994) Den naturhistoriske samling og forskningen. Nordisk Museologi 2: 47–56.
  • 83. Karsholt O, Kristensen NP, Kozlov MV (1994) Eriocrania cicatricella (Zetterstedt, 1839) the correct name of the moth currently known as Eriocrania haworthi Bradley, 1966 (Lepidoptera: Eriocraniidae). Entomologiske Meddelelser 62: 91–93.
  • 82. Melzer RR, Kristensen NP, Paulus HF (1994)The larval eye of nannochoristid scorpionflies (Insecta, Mecoptera). Acta Zoologica 75: 201–208. doi: 10.1111/j.1463-6395.1994.tb01207.x
  • 81. Kristensen NP, Nielsen ES (1994) Osrhoes coronta Druce, the New World palaeosetid moth: A reappraisal, with description of a new type of female genital apparatus (Lepidoptera, Exoporia).Entomologica scandinavica 24: 391–406. doi: 10.1163/187631293X00181
  • 80. Kristensen NP (1994) Må man gerne samle på insekter? Dyr i Natur og Museum 1994/1: 7–10.
  • 79. Kristensen NP (1994) Bent W. Rasmussen. Entomologiske Meddelelser 62: 95.
  • 78. Kristensen NP (1994) Karl Georg Wingstrand. Det Kongelige danske videnskabernes Selskab. Oversigt over Selskabets Virksomhed 1992–93: 155–166.
  • 77. Kristensen NP (1993) En enestående tilgang til Zoologisk Museums sommerfuglesamling. Dyr i Natur og Museum 1993/2: 2022.
  • 76. Kristensen NP (1993) Biodiversitetens dimensioner: kvantitet og ’kvalitet’. Naturens Verden 1993: 163179. [with contributions from Andersen, P. F., Coull, B., de Kalin Arrogo, M., Friis, I., Greuter, W., Ihlenfeldt, H.D. & Strid, A.]
  • 75. Kristensen NP, Rasmussen JF (1993) Biodiversitet som videnskabelig og samfundsmæssig udfordring. Naturens Verden 1993: 197208. [with contributions from Ehrlich, P. R., Fjeldså, F., Janzen, D. H., Strid, A. & von Bothmer, R.]
  • 74. Kristensen NP, Larsen K (1993) Biodiversitet i en verden under forandring. Naturens Verden 1993: 161–162.
  • 73. Kristensen NP (1991) Phylogeny of extant hexapods. Pp.125–140 in CSIRO (ed.): The Insects of Australia. Carlton: Melbourne University Press.[Reprinted with minor alterations in I.D. Naumann (ed.) Systematic and Applied Entomology. An Introduction (1994). Carlton: Melbourne University Press.
  • 72. Kristensen NP (1990) Morphology and phylogeny of the lowest Lepidoptera-Glossata: Recent progress and unforeseen problems. Bulletin of the Sugadaira Montane Research Center 11: 105–106.
  • 71. Kristensen NP (1990) The trunk integument of zeuglopteran larvae: One of the most aberrant arthropod cuticles known (Insecta, Lepidoptera). Bulletin of the Sugadaira Montane Research Center 11: 101–102.
  • 70. Kristensen NP (1990) Den ‘eksploderede’ goliathbille. Dyr i Natur og Museum 1990/2: 29.
  • 69. Kristensen NP (1990) Torben W. Langer *7.6.1924 †13.4.1988. Entomologiske meddelelser 58: 95–96.
  • 68. Nielsen ES, Kristensen NP (1989) Primitive Ghost Moths. Monographs on Australian Lepidoptera, 1, 1–206, CSIRO, Canberra.
  • 67. Kristensen NP (1989) Insect phylogeny based on morphological evidence. Pp 295–306 in Fernholm, B. et al. (eds): The Hierarchy of Life. Molecules and Morphology in Phylogenetic Analysis. Amsterdam: Elsevier.
  • 66. Kristensen NP (1989) The New Zealand scorpionfly (Nannochorista philpotti comb.n.): wing morphology and its phylogenetic significance. Zeitschrift für zoologische Systematik und Evolutionsforschung 27: 106–114. doi: 10.1111/j.1439-0469.1989.tb00335.x
  • 65. Kristensen NP (1988) Biography and contributions of prof. dr Jean Chaudonneret, 1984 Recipient of The Distinguished International Award in Insect Morphology and Embryology. International Journal of Insect Morphology and Embryology 17: 171–176. doi: 10.1016/0020-7322(88)90034-7
  • 64. Kristensen NP (1986) Nachruf Anker Nielsen. Trichoptera Newsletter 13: 4–6.
  • 63. Kristensen NP (1985) De første snabelsommerfugle. Dyr i Natur og Museum 1985/2: 10–12.
  • 62. Kristensen NP (1985) Sommerfuglenes tidligste udvikling. Dyr i Natur og Museum 1985/1: 14–18.
  • 61. Kristensen NP (1985) Sommerfuglenes storsystematik/The higher classification of Lepidoptera. In: Schnack, K. (ed.): Katalog over de danske Sommerfugle. Entomologiske Meddelelser 52/2–3: 6–20.
  • 60. Kristensen NP (1985) Anker Nielsen: 21. februar 1907 – 9. december 1984. Videnskabelige Meddelelser fra dansk naturhistorisk Forening 146: 115–124.
  • 59. Kristensen NP (1984) Studies on the morphology and systematics of primitive Lepidoptera (Insecta). Steenstrupia 10: 141–191.
  • 58. Kristensen NP (1984) The male genitalia of Agathiphaga (Lepidoptera, Agathiphagidae) and the lepidopteran ground plan. Entomologica Scandinavia 15: 151–178. doi: 10.1163/187631284X00127
  • 57. Kristensen NP (1984) The larval head of Agathiphaga (Lepidoptera, Agathiphagidae) and the lepidopteran ground plan. Systematic Entomology 9: 63–81. doi: 10.1111/j.1365-3113.1984.tb00502.x
  • 56. Kristensen NP (1984) The pregenital abdomen of the Zeugloptera (Lepidoptera). Steenstrupia 10: 113–136.
  • 55. Kristensen NP (1984) Respiratory system of the primitive moth Micropterix calthella (Linnaeus) (Lepidoptera: Micropterigidae). International Journal of Insect Morphology and Embryology 13: 137–156. doi: 10.1016/0020-7322(84)90022-9
  • 54. Kristensen NP (1984) Skeletomuscular anatomy of the male genitalia of Epimartyria (Lepidoptera: Micropterigidae). Entomologica Scandinavia 15: 97–112. doi: 10.1163/187631284X00091
  • 53. Kristensen NP (1984) S. L. Tuxen. International Journal of Insect Morphology and Embryology 13: 311–314. doi: 10.1016/0020-7322(84)90007-2
  • 52. Kristensen NP (1984) S. L. Tuxen. Videnskabelige Meddelelser fra Dansk naturhistorisk Forening 144: 157–170.
  • 51. Kristensen NP, Nielsen ES (1983) The Heterobathmia life history elucidated: Immature stages contradict assignment to suborder Zeugloptera (Insecta, Lepidoptera). Zeitschrift für zoologische Systematik und Evolutionsforschung 21: 101–124. doi: 10.1111/j.1439-0469.1983.tb00280.x
  • 50. Kristensen NP, Nielsen ES (1982) South American micropterigid moths: two new genera of the Sabatinca-group (Lepidoptera: Micropterigidae). Entomologica Scandinavia 13: 513–529. doi: 10.1163/187631282X00318
  • 49. Henriksen HJ, Kristensen NP (1982) Dagsommerfuglen Colias alfacariensis, en nyopdaget strejfgæst i Danmark (Lepidoptera: Pieridae). Entomologiske Meddelelser 49: 123–131.
  • 48. Kristensen NP. (1982) Splittng or widening: remarks on the taxonomic treatment of paraphyletic taxa. Annales Zoologici Fennici 19: 201–202.
  • 47. Kristensen NP, Nielsen ES (1981) Double-tube proboscis configuration in neopseustid moths (Lepidoptera: Neopseustidae). International Journal of Insect Morphology and Embryology 10: 483–486. doi: 10.1016/0020-7322(81)90027-1
  • 46. Kristensen NP, Nielsen ES (1981) Intrinsic proboscis musculature in non-ditrysian Lepidoptera-Glossata: Structure and phylogenetic significance. Entomologica Scandinavia Supplement 15: 299–304.
  • 45. Kristensen NP, Nielsen ES (1981) Abdominal nerve cord configuration in adult non-ditrysian Lepidoptera. International Journal of Insect Morphology and Embryology 10: 89–91. doi: 10.1016/0020-7322(81)90015-5
  • 43. Kristensen NP (1981) Amphiesmenoptera. Trichoptera. Lepidoptera. Pp. 325–330, 412–415 in Hennig, W.: Insect Phylogeny (Pont & Schlee eds). Chichester, New York, Brisbane, Toronto: John Wiley & Sons.
  • 42. Kristensen NP (1980). Sesia andrenaeformis Laspeyres, 1801 (Insecta, Lepidoptera): Proposed conservation. Z.N.(S) 2139. Bulletin of Zoological Nomenclature 37: 156–157.
  • 41. Kristensen NP (1980) Sphinx tipuliformis Clerck, 1759 (Insecta, Lepidoptera): Proposed conservation. Z.N.(S) 2138. Bulletin of Zoological Nomenclature 37: 154–156.
  • 40. Kristensen NP, Nielsen ES (1980) The ventral diaphragm of primitive (non-ditrysian) Lepidoptera. A morphological and phylogenetic study. Zeitschrift für zoologische Systematik und Evolutionsforschung 18: 123–146. doi: 10.1111/j.1439-0469.1980.tb00734.x
  • 39. Kristensen NP, Nielsen ES (1979) A new subfamily of micropterigid moths from South America. A contribution to the morphology and phylogeny of the Micropterigidae, with a generic catalogue of the family (Lepidoptera: Zeugloptera). Steenstrupia 5: 69–147.
  • 38. Kristensen NP (1979) Wilhelm van Deurs in memoriam. Lepidoptera NS 3: 191–192.
  • 37. Heath J, Kristensen NP Nielsen ES (1979) On the identity of Tinea tunbergella Fabricius, 1987 and Tinea thunbergella Fabricius, 1794 (Lepidoptera: Micropterigidae, Gracillariidae). Entomologica Scandinavia 10: 9–12. doi: 10.1163/187631279X00358
  • 36. Kristensen NP (1979) H. Bruce Boudreaux: Arthropod Phylogeny with Special Reference to Insects. Systematic Zoology 28: 638–643.
  • 35. Kristensen NP (1979) The Mnesarchaea proboscis, a correction. Entomologica Generalis 5: 267–268.
  • 34. Kristensen NP (1978) A new familia of Hepialoidea from South America, with remarks on the phylogeny of the subordo Exoporia (Lepidoptera). Entomologica Germanica 4: 272–294.
  • 33. Kristensen NP (1978) Ridge dimorphism and second-order ridges on wing scales in Lepidoptera: Exoporia. International Journal of Insect Morphology and Embryology 7: 297–299. doi: 10.1016/0020-7322(78)90010-7
  • 32. Kristensen NP (1978) Observations on Anomoses hylecoetes (Anomosetidae), with a key to the hepialoid families (Insecta, Lepidoptera). Steenstrupia 5: 1–19.
  • 31. Kristensen NP (1978) Obituary: Henning Lemche. Bulletin of Zoological Nomenclature 35: 5–6.
  • 30. Kristensen NP (1978) Phylogenetic methodology in hexapod high-level systematics: Results and perspectives. Norwegian Journal of Entomology 25: 84–85.
  • 29. Kristensen NP (1976) A redescription of the male genital morphology of Paramartyria immaculatella (Insecta, Lepidoptera, Micropterigidae). Steenstrupia 4: 27–32.
  • 28. Kristensen NP (1976) Remarks on the family-level phylogeny of butterflies (Insecta, Lepidoptera, Rhopalocera). Zeitschrift für zoologische Systematik und Evolutionsforschung 14: 25–33. doi: 10.1111/j.1439-0469.1976.tb00515.x
  • 27. Rothenborg HW, Sjølin K-E, Kristensen NP (1976) Sandlopper. Souvenirs fra tropeferien. Ugeskrift for Læger 1976: 2437–2440.
  • 26. Kristensen NP (1975) The phylogeny of hexapod “orders”. A critical review of recent accounts. Zeitschrift für zoologische Systematik und Evolutionsforschung 13: 1–44. doi: 10.1111/j.1439-0469.1975.tb00226.x
  • 25. Kristensen NP (1975) On the evolution of wing transparency in Sesiidae (Lepidoptera). Videnskabelige Meddelelser fra Dansk naturhistorisk Forening 137: 125–134.
  • 24. Fibiger M, Kristensen NP (1974) The Sesiidae (Lepidoptera) of Fennoscandia and Denmark. Fauna Entomological Scandinavia 2: 1–91.
  • 23. Birket-Smith S, Kristensen NP (1974) The skeleto-muscular anatomy of the genital segments of male Eriocrania (Insecta, Lepidoptera). Zeitschrift für Morphologie und Ökologie der Tiere 77: 157–174. doi: 10.1007/BF00374214
  • 22. Achtelig M, Kristensen NP (1974) A re-examination of the relationships of the Raphidioptera (Insecta). Zeitschrift für zoologische Systematik und Evolutionsforschung 11: 268–274. doi: 10.1111/j.1439-0469.1973.tb00147.x
  • 21. Karsholt O, Kristensen NP (1974) Undersøgelser over sommerfuglefaunaen på Hesselø. Entomologiske Meddelelser 42: 33–47.
  • 20. Kristensen NP (1972) Et fund af Dysgonia algira i Danmark (Noctuidae). Lepidoptera (N. S.) 2: 106–107.
  • 19. Kristensen NP (1972) Sommerfuglenes stilling i insektsystemet. Lepidoptera (N. S.) 2: 61–67.
  • 18. Kristensen NP, Jelnes JE (1972) Om navngivning af ”aberrationer”. Flora & Fauna 78: 25.
  • 17. Kristensen NP (1971) Dagsommerfuglenes storsystematik. En oversigt over nyere undersøgelser. Entomologiske Meddelelser 39: 201–233.
  • 16. Kristensen NP (1971) Sikre bestemmelseskarakterer hos hunnerne af Adopaea lineola og A. flava (Lep., Hesperiidae). Entomologiske Meddelelser 39: 133–136.
  • 15. Kristensen NP (1971) Et sjællandsk eksemplar af Nymphalis xanthomelas (Lep., Nymphalidae). Entomologiske Meddelelser 39: 129–132.
  • 14. Kristensen NP (1971) The systematic position of the Zeugloptera in the light of recent anatomical investigations. Proceedings of the XIIIth international Congress of Entomology in Moscow, 2–9 August 1968 1: 261.
  • 13. Kristensen NP, Kaaber S, Wolff NL (1971). Europas dagsommerfugle. 266 pp. Gads Forlag, København. [Translated and revised edition of: L. G. Higgins & N. D. Riley (1970). A field guide to the butterflies of Britain and Europe].
  • 12. Kristensen NP (1970) Systematisk Entomologi. Munksgaards Forlag, Copenhagen. 173 pp.
  • 11. Kristensen NP (1970) Morphological observations on the wing scales in some primitive Lepidoptera (Insecta). Journal of Ultrastructure Research 30: 402–410. doi: 10.1016/S0022-5320(70)80071-5
  • 10. Kristensen NP (1968) The anatomy of the head and the alimentary canal of adult Eriocraniidae (Lep., Dacnonypha). Entomologiske Meddelelser 36: 239–315.
  • 9. Kristensen NP (1968) The skeletal anatomy of the heads of adult Mnesarchaeidae and Neopseustidae (Lep., Dacnonypha). Entomologiske Meddelelser 36: 137–151.
  • 8. Kristensen NP (1968) The morphological and functional evolution of the mouthparts in adult Lepidoptera. Opuscula Entomologica 33: 69–72.
  • 7. Kristensen NP (1967) A note on Chapmania kaltenbachi sensu Hering 1932 (Lep., Eriocraniidae). Entomologiske Meddelelser 35: 346–348.
  • 6. Kristensen NP (1967) Erection of a new family in the Lepidopterous suborder Dacnonypha. Entomologiske Meddelelser 35: 341–345.
  • 5. Kristensen NP (1966) Om sæsondimorfien hos Plusia chrysitis (L.) (Lepidoptera, Noctuidae). Flora & Fauna 72: 155–158.
  • 4. Kristensen NP (1966) Notes on Sterrha ochrata, a moth new to the Danish fauna (Lep., Geometridae). Entomologiske Meddelelser 34: 214–220.
  • 3. Kristensen NP (1966) On the subgeneric position of Orthosia porosa (Lep., Noctuidae). Entomologiske Meddelelser 34: 211–213.
  • 2. Kristensen NP (1965) Cikaden Eupteroidea stellulata (Burmeister 1841) i Danmark. (Hemiptera, Cicadellidae). Flora & Fauna 71: 81–82.
  • 1. Kristensen NP (1965) Cikader (Homoptera auchenorrhyncha) fra Hansted-reservatet. Entomologiske Meddelelser 30: 269–287.
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