Formicinae, Formicidae, Hymenoptera, Insecta, Arthropoda, Animalia
Scape extremely long and lacking macrochaetae or suberect pubescence of any kind; integument with bluish reflections.
This species is a pantropical tramp that is easily dispersed by human activity. They are a common pest ant in houses and seem peculiarly adapted to the interior and immediate vicinity of human habitations (Fig. 1). In Costa Rica I have collected them in the town squares of Liberia and Sierpe, city parks in San Josˇ, around the buildings at Finca La Pacifica, beach margins of Atlantic and Pacific coasts, and in the dining hall of La Selva Biological Station. At La Selva, where intensive surveys of the ant fauna have been carried out, I have never collected P. longicornis beyond the confines of the dining hall.
The workers are very generalized scavengers, very quickly recruiting to food scraps in houses.
On two occasions, once at Discovery Bay Marine Lab in Jamaica and once on the steps of the La Selva dining hall, I have seen massive emergences of P. longicornis colonies (Fig. 2). I do not know what caused these evacuations, but the visual effect was stunning. In each case many square meters were covered with a coruscating layer of workers. The workers formed a closely spaced monolayer. Many of the workers were carrying brood, and many dealate queens were scattered amongst the workers. When undisturbed the ants were more or less stationary, but shining a light on them or blowing on them caused ripples and waves of movement.
There is a large literature on the biology of P. longicornis. A search for "Paratrechina longicornis" in the 2001 version of Formis, a database of ant literature, yielded 271 references.
John T. Longino, The Evergreen State College, Olympia WA 98505 USA.firstname.lastname@example.org
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