Throughout the mainland Neotropics, from Guatemala to Brazil and Bolivia. In Costa Rica: throughout the country in wet forest areas, to 1500m elevation in Monteverde.
This species forms very large colonies. Nests may fill large rotten stumps or rotten logs (figures below). Often tell-tale piles of sawdust surround such nests, from workers excavating the interior. Workers are aggressive, and forage day or night. Large numbers of minor and major workers may be observed swarming out from nests and retrieving live insect prey, with a behavior reminiscent of army ants (figure). Kugler (1979) has termed this "gang-pulling." Workers also have an enlarged pygidial gland that segretes a noxious gummy substance used in defense (Kugler 1979). Workers tend Homoptera and visit extrafloral nectar sources. Colonies may build scattered carton shelters on low vegetation and tend membracids and other Homoptera beneath them. Workers may aggressively defend extrafloral nectar sources (e.g. Passiflora shoots), driving away herbivores and other ants. Colonies use carton construction to form baffles in rotten wood, and galleries running up tree trunks. At Rara Avis, workers were observed tending large riodinid larvae under carton galleries (figure).
Founding queens are found under loose bark of dead wood, in dead branches, and very commonly under epiphyte mats on recently fallen trees.
In Penas Blancas, Longino observed an interaction with phorid flies. Workers were streaming up a tree trunk. Phorids were hovering above. One landed on the head of a soldier. Afterwards, workers grabbed the soldier by the legs and slowly began to drag it down the trunk.
biconstricta is a complex lineage with many infraspecific taxa in the taxonomic literature. Four of these have type localities in Costa Rica:
biconstricta surda Forel 1912:222
biconstricta bicolor Emery 1890:50
biconstricta bicolor regina (unavailable quadrinomial)
biconstricta rubicunda Emery 1890:50
Wilson (2003) synonymized them all under biconstricta.
In Costa Rica, specimens from the southern Pacific lowlands are light orange. In Monteverde, they are two-toned, with light orange head and mesosoma, and somewhat darker gaster. On the Atlantic slope they are brown to dark brown. The transition can be sharp: specimens of the two-toned Monteverde form are known from open areas in and around Monteverde, on the Pacific slope west of the cloud forest that covers the continental divide; the dark brown form is common in the Penas Blancas Valley, about 5km east of Monteverde on the Atlantic slope. There is also variation in sculpture, but it does not show geographic patterns and varies within populations.
Kugler, C. 1979. Alarm and defense: a function for the pygidial gland of the myrmicine ant, Pheidole biconstricta. Annals of the Entomological Society of America 72:532-536.
Wilson, E. O. 2003. Pheidole in the New World: A Dominant, Hyperdiverse Ant Genus. Harvard University Press, Cambridge, Mass
Found most commonly in these habitats: 38 times found in tropical wet forest, 13 times found in montane wet forest, 22 times found in 2º wet forest, 12 times found in mesophil forest, 9 times found in wet forest, 3 times found in secondgrowth rainforest, 2 times found in 2º lowland rainforest, 4 times found in cloud forest, 2 times found in scrub forest, 1 times found in 2nd growth wet forest, ...
Collected most commonly using these methods or in the following microhabitats: 53 times Baiting, 35 times search, 18 times MiniWinkler, 12 times Beating, 7 times Winkler, 4 times MaxiWinkler, 4 times Sweeping, 2 times bait, 1 times in rotting log, 2 times Lure/Bait, 1 times Berlese, ...
Elevations: collected from 20 - 1500 meters, 758 meters average