Carl Rettenmeyer

He spent his later years examining samples from 1600 army ant colonies he had collected and in total found 45,000 mites.

Of these mites, only 3% have been studied and whilst doing so, three new mite families were identified as well as over 100 new species.

Those identified often have inconceivably strange lifestyles.

Carl W. Rettenmeyer (February 10, 1931 – April 9, 2009) was an American biologist who specialised in army ants.

He was born in Meriden, Connecticut, and later attended Swarthmore College in Pennsylvania.

He first became interested in army ants when he visited Panama as an undergraduate and then returned there as a postgraduate.

Although he studied many aspects of army ant biology, he particularly focused on the animals associated with the ants and especially mites which live on the ants.

He was well known for his photography of army ants, with his photographs appearing in over 100 publications, and he used his video footage to create two DVDs.

He first met his wife Marian at a summer school at the University of New Hampshire in 1951 and married her in 1955.

She had been interested in insects from an early age and Rettenmeyer "knew she was a woman I had to keep track of"; she would become his lifelong assistant.

Together they had a son and a daughter.

Rettenmeyer attended Swarthmore College as an undergraduate, majoring in Biology and graduated in 1953.

Whilst in his junior year he was contacted by Theodore Schneirla, an acquaintance of his professor.

Schneirla was studying the behaviour of army ants and needed an assistant to work for six months on Barro Colorado Island (BCI) in Panama, which Rettenmeyer accepted.

Schneirla was interested in army ants behaviour as he thought that by studying it he could understand how it would be possible for humans to fight wars more effectively.

They spent many nights observing army ant trails and it was at this time that Rettenmeyer first noticed that other animals lived on the ants.

a subject that continued to fascinate him throughout his life.

He taught at the University of Kansas from 1960 until 1971 and then at the University of Connecticut until his retirement in 1996, after being diagnosed with Waldenstrom’s macroglobulinemia.

After graduating he studied a PhD in entomology at the University of Kansas under the supervision of Charles Duncan Michener, which he completed in 1962.

During his PhD Life magazine approached him asking him to accompany a photographer to BCI to photograph army ants.

Rettenmeyer says that this was his "lucky break" and during nine weeks spent on BCI he collected thousands of specimens, including 147 species of mite found living on the ants.

Upon his return to Kansas he was encouraged by faculty members to apply for funding so he could return to study army ants in the rainforest.

Through his career he went on over 20 expeditions to Panama, Ecuador and Costa Rica.

Rettenmeyer studied a broad range of topics related to army ants, publishing on general army ant biology, chemical communication and foraging behaviour.

His work also inspired other researchers to investigate such diverse areas as avian ecology, social insect symbioses, tropical phenology and conservation biology.

He presented at many conferences and published over 50 papers during his career.

In 1963, Rettenmeyer rediscovered the army ant Neivamyrmex sumichrasti, which was first described by François Sumichrast in the 1860s but then not studied further.

In 1975 he reported in Science the first recorded case of mass recruitment in army ants.

He found that when worker ants encountered a food source that was too large for them to kill or carry themselves, they can communicate with other workers via chemical and physical signals to recruit them to assist.

Working with his wife, Rettenmeyer identified 557 species of animals associated with Eciton burchellii, the greatest number of animals known to associate with any single animal species.

Although many of the associations are likely to be opportunistic, over 300 species are thought to be reliant on the ant to survive.

As well as these species, Rettenmeyer collected many thousands of specimens that have not been identified.

In 1996 he was diagnosed with Waldenstrom’s macroglobulinemia, a form of lymphoma and expected to die within a few years.

Although he retired the same year, a new drug developed soon after his diagnosis kept the disease in check, allowing him to continue to work, despite often having to use a wheelchair due to his frailty.

He continued to correspond with other army ant researchers with enthusiasm after retiring.

In 2003, he helped another expedition find the species again, and also tried to find a species of beetle associated with it.

However, Ecitosius robustus, the robust army ant beetle, is almost impossible to distinguish physically from the host ant, and Rettenmeyer was unable to find it among the samples collected.

He was one of the first biologists to visit Monteverde Cloud Forest Reserve in Costa Rica, which is now a major center for Neotropical research.

After his death in 2009, a set of papers on army ants were published in Insectes Sociaux in memory of his work.

Rettenmeyer was born in Meriden, Connecticut, to his parents Frederick and Gertrude; he had one sister.