Hawaii Ant Group (HAG)
The Hawaii Ant Group (HAG) is dedicated to the better understanding of ants (Hymenoptera: Formicidae) and their impacts in Hawaii. |
Little fire ant (Wasmannia auropunctata) distribution maps (Hawaii) - are now online! |
Ant Photos
- available for public use
See also the ant key |
by Neil Reimer
U.S. Department of Agriculture, Plant Quarantine Branch, 701 Ilalo Street, Honolulu, HI 96813
voice: (808) e-mail:
A total of 44 ant species have been recorded in the Hawaiian Islands. None of these ants are native. They were all accidentally introduced by people. Ants have a devastating impact on the native fauna and flora. In the absence of ants, Hawaii's endemic fauna never evolved adaptations such as mimicry, or distasteful or appeasement secretions to thwart predation by ants, as is commonly observed with invertebrates from areas where ants are endemic. The establishment of ants over wide areas could result in the reduction and possible elimination of many native plant pollinators, threatening reproductive success. Certain ant species are also efficient seed predators.
Because of the severe impact ants can have on Hawaii's native fauna and flora, it is critical that native habitats be surveyed and monitored regularly for pestiferous ants so that adequate management strategies can be developed. It is important to determine the identity of the ant species present before an ant management program can be initiated, because ant behavior, biology, and ecology vary among species. Control strategies must be developed which are appropriate for the specific ant species. Ant Survey and Control Methods are provided in this key.
There are 16 ant species that are common or occasionally found in undeveloped habitats (non-urban and non-agricultural), and a few other ant species which are rarely encountered in undeveloped habitats. The ant species in this key are those that are most likely to cause a significant impact on Hawaii's native biota. Other species tend not to have a significant impact or are rarely encountered in undeveloped habitats.
CAUTION! Keep in mind that this key only addresses the 16 most pestiferous ant species commonly found in undeveloped habitats. Remember that there are roughly 44 ant species in the islands.
If your ant specimen doesn't seem to fit the photo or caption and there are no other options, then you may have one of the few ant species that are rarely found in undeveloped habitats or you may have found a species new to Hawaii. Please help prevent a new pest outbreak by submitting specimens to Neil Reimer at the address below.
IF YOU NEED HELP TO IDENTIFY YOUR ANT SPECIMENS, CONTACT:
Neil Reimer, Department of Agriculture, Plant Quarantine Branch, 701 Ilalo Street, Honolulu, HI 96813
voice: (808) e-mail:
Some ant species (e.g. Hypoponera opaciceps) may be present but will never cause any significant problems to the environment, mainly due to the small colony size. No attempts at controlling this species will be needed. Other species can cause serious problems and should be controlled, such as the big-headed ant (Pheidole megacephala), Argentine ant (Linepithema humile), long-legged ant (Anoplolepis longipes), fire ant (Solenopsis geminata), Solenopsis papuana, and the black house ant (Ochetellus glaber). These ant species build large populations of interconnected colonies, occupy acres of land, and dominate the environment. Control of these ants is essential to prevent the decimation of the native fauna and flora.
Control of ants in natural habitats is often difficult and problematic. Reasons for the difficulty in ant management in natural habitats include: 1) the terrain; 2) undesirable effects of ant control methods on non-target organisms; 3) abundance of naturally occurring food; and 4) changes in food preferences due to ant developmental stages.
The terrain. Ants often occupy extensive areas of rough or inaccessible terrain. It may on occasion be difficult or impossible to gain access to these areas by foot. The result is that it can be quite expensive just to get to the infested area, let alone attempt to control the ants.
Romero, Hernan, and Klaus Jaffe. 1989. A comparison of methods for sampling ants (Hymenoptera: Formicidae) in savannas. Biotropica 21(4): 348-352.
Perkins, R. C. L. 1913. Introduction. Fauna Hawaiiensis 1(6): i-ccxxvii(xli-xlii).
Romero, Hernan, and Klaus Jaffe. 1989. A comparison of methods for sampling ants (Hymenoptera: Formicidae) in savannas. Biotropica 21(4): 348-352.
Anoplolepis longipes (Jerdon) [long-legged ant]
Color: reddish
Size: 1/4"
Nodes One (node=segment between thorax and abdomen)
Other Characters: long legs and antennae; slim body;
Behavior: individuals are fast moving;
Colonies: are large (>200 workers, many queens) and interconnected;
Nest: in rock piles and rock walls;
Habitat: found in dry, mesic, and wet areas below 3,000 ft. elevation;
Foraging Behavoir: workers forage by spreading over foraging area, rarely form trails except up trees or over narrow passages;
Camponotus variegatus (Fr. Smith) [carpenter ant]
Color: reddish to light brown
Size: 1/2"; some workers with larger heads than others;
Nodes: one
Other characters: largest ant species in the islands;
Behavior:
Colonies: often small (20 to 200 individuals, many queens);
Nest: nest in wood, under logs, or under or in any undisturbed, dry covering;
Habitat: found throughout the islands in most habitats;
Foraging Behavoir: workers forage singly, never form trails unless moving young;
Cardiocondyla venustula Wheeler
Color: brown to black
Size: 1/8"; all one size
Nodes: two
Other characters:
Behavior:
Colonies: often small (20 to 200 individuals, many queens);
Nest: under rocks and debris
Habitat: found from 0 to 10,000 feet elevation in dry, mesic and wet climates
Foraging Behavoir: single foragers, don't form trails
Hypoponera opaciceps (Mayr)
Color: black
Size: 1/8"
Nodes: one
Other characters:
Behavior: fairly slow movers,
Colonies: small (<50 workers, one queen)
Nest: in soil, decaying wood, under stones
Habitat: most commonly in mesic to wet areas above 2,000 feet;
Foraging Behavoir: single foragers, no trails
Linepithema humile (Mayr) [Argentine ant]
Color: brown
Size: 1/8"
Nodes: one
Other characters:
Behavior:
Colonies: large (>100 workers, many queens), interconnected to other colonies
Nest: under stones
Habitat: found from 0 to 10,000 feet, more commonly above 3,500 feet in dry or mesic habitats
Foraging Behavoir: single foragers but also form trails to food and between nests
Monomorium floricola (Jerdon)
Color: bicolored, head and abdomen dark brown, thorax lighter brown to yellow;
Size: 1/16"
Nodes: two
Other characters: very small and thin;
Behavior: will sting
Colonies: large (>100 workers, many queens)
Nest: in twigs and branches and under bark of trees and shrubs
Habitat: dry and mesic areas below 3,000 feet
Foraging Behavoir: form trails along ground and in trees
Ochetellus glaber (Mayr) [glaber ant]
Color: black
Size: 1/8"
Nodes: one
Other characters:
Behavior: will bite; feeds on honeydew from aphids and mealybugs
Colonies: large (>100 workers, many queen), interconnected
Nest: in soil, under logs and rocks
Habitat: dryer areas below 3,000 feet
Foraging Behavoir: workers form trails
Paratrechina bourbonica (Forel) [crazy ant]
Paratrechina longicornis (Latreille) [crazy ant]
Color: black for P. bourbonica, black with purple irridescence for P. longicornis
Size: 1/8"
Nodes: one
Other characters: long legs and antennae for P. longicornis; more robust for P. bourbonica
Behavior: fast runner, especially when disturbed; feeds on honeydew
Colonies: large (>200 workers, one queen)
Nest: in soil under stones and debris
Habitat: dry areas below 3,000 feet
Foraging Behavoir: forms trails
Pheidole megacephala (Fabricius) [big-headed ant]
Color: brown
Size: 1/8"; some workers with large heads
Nodes: two
Other characters:
Behavior:
Colonies: large (>200 workers, many queens)
Nest: in soil, sometime with donut of dirt around hole
Habitat: found in dry and mesic areas below 3,000 feet;
Foraging Behavoir: workers forage by spreading over foraging area but will forms trails up trees and to food sources
Plagiolepis alluaudi Forel [little yellow ant]
Color: yellow
Size: 1/16"
Nodes: one
Other characters:
Behavior: tends insects for honeydew
Colonies: large (>50 workers, many queens)
Nest: in trees
Habitat: dry and mesic areas below 3,000 feet
Foraging Behavoir: forms trails
Solenopsis geminata (Fabricius) [fire ant]
Color: red
Size: 1/8"; workers range in size from less than 1/8" to about 1/4"; some with large heads
Nodes: two
Other characters:
Behavior: will sting aggressively; tends insects for honeydew
Colonies: large (>200, many queens)
Nest: in soil often with piles of dirt around entrance
Habitat: dry areas below 1,000 feet, in leeward areas of islands
Foraging Behavoir: workers forage by spreading over foraging area, will form trails
Solenopsis papuana Emery
Color: black
Size: 1/16", all workers of same size
Nodes: two
Other characters: antennae with 2 segmented club
Behavior:
Colonies: large (>1000 workers, many queens)
Nest: in soil under rocks, most often associated with rotting wood in or near soil
Habitat: found mainly in mesic and wet forested areas between 1,000 and 3,500 feet
Foraging Behavoir: form trails but workers also forage by spreading over foraging area
Tapinoma melanocephalum (Fabricius) [tiny yellow house ant]
Color: bicolored, black head with yellow abdomen and thorax
Size: 1/16"; all workers of same size
Nodes: one but appears as none
Other characters:
Behavior: very fast mover
Colonies: large (>200 workers, many queens)
Nest: under rocks
Habitat: found in dry and mesic areas below 2,000 feet
Foraging Behavoir: forms trails
Technomyrmex albipes (Fr. Smith)
Color: brown to black with white feet (not easily seen)
Size: 1/8"
Nodes: one but may appear as none
Other characters:
Behavior: tend insects for honeydew
Colonies: small or large (>200 workers, many queens)
Nest: in trees
Habitat: found in dry, mesic, and wet areas below 5,000 feet
Foraging Behavoir: form trails
Tetramorium simillimum (Fr. Smith)
Color: brown; sometimes abdomen appears dark brown and head and thorax are light brown
Size: 1/8"
Nodes: two
Other characters:
Behavior:
Colonies: large (>100 workers, many queens)
Nest: in soil
Habitat: found most commonly in dry lowland areas
Foraging Behavoir: forms trails
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