Crazy ant

Identification

Crazy ants (Paratrechina spp.) get their name from the habit of meandering around and not following trails as often as other ants.  Instead of looking focused (following distinct trails), they are often seen wandering around countertops, floors, etc., as if they are lost. These ants can be confused with rover and Argentine ants, but are easy to distinguish by observing their rapid and erratic movements.

Another key to identifying crazy ants is the lack of a sting; confirmation may be made with the aid of a hand lens through which the extremely long legs and erect hairs can be seen. These ants are also small (2-3 mm) and slender and appear to be all the same size. They are black or gray and often have a faint, bluish iridescence. Workers have slender bodies and long legs and are capable of extremely rapid movement.

 Foraging and Feeding

Workers are omnivorous, feeding on live and dead insects, seeds, honeydew, fruits, plant exudates and many household foods. The crazy ant thrives in places such as gasoline stations, convenience stores and sidewalk cafes where workers may be seen transporting crumbs and insects attracted to lights. They apparently have a seasonal preference for a high-protein diet, and during the summer months may refuse honey or sugar baits. They are attracted to honeydew-producing homopterans (aphids, mealy bugs, etc.) in spring and fall.

Workers are known to gather small seeds of such crops as lettuce and tobacco from seedbeds. In cold climates, the ants nest in apartments and other buildings where they are potential pests year round. Workers feed on many household foods such as meats, grease, sweets, fruits, vegetables and liquids.

 Nest Sites

Crazy ants are highly adaptable, living in both dry and moist habitats. Nests can be established a considerable distance away from their foraging area and are often found in such places as trash, refuse, cavities in plants and trees, rotten wood or in soil under objects. A crazy ant nest site can be found by looking for workers carrying food back to the nest.

It will not be easy to spot mounds in your lawn. These ants will nest in soil beneath landscape timbers, mulch, decorative stone, logs, firewood and debris such as abandoned construction material. They can also be found in rotting wood, holes in the trunks and limbs of trees, and even irrigation equipment.

During periods when the ants are foraging, trails are easily observed on the sides of the home and on sidewalks, patios and driveways. As with any ant trail, the ants will be seen traveling in opposite directions. While some of the workers are marching towards their food source, the others are carrying food back to their nest.   Those carrying food should be followed to locate the ant nest for elimination. If visible pieces of food are not seen by the returning ants, their abdomen will appear swollen from carrying liquids being carried back to the ant colony.

 Management

While inspecting for crazy ant colonies in and around the house, you should locate as many entry points as possible. Tree limbs or other vegetation touching the structure are "bridges" for these tiny pests. They have also been observed living in small pebbles or other such materials on buildings that have a flat roof. 

Non-chemical control is based on exclusion through good housekeeping practices and cleanliness by eliminating food sources. Crazy ants nest outdoors, so preventing their entrance by caulking exterior penetrations and weather-stripping may aid in their control. Indoor chemical controls are based on baits, dusts and spot treatments with residual sprays. Outdoor treatments include chemical formulations such as baits, granules, dusts and sprays. Always read and follow label instructions and precautions before using any insecticide.

Homeowners should look for foraging trails indoors and place liquid baits accordingly. Crazy ants will attend solid baits sporadically, particularly in the spring when they need protein for colony growth. During dry seasons, these ants may come indoors in search of water, and therefore liquid baits are effective. The use of a contact insecticide as a barrier will help to prevent them from entering, and be sure to seal any cracks and crevices or other areas that might allow entry. Remove any vegetation that is in contact with the structure that might provide bridges ants can use to bypass barriers and enter structures. If possible, find the nests and soak them with a contact insecticide to control the population.

 Further Reading

Creighton W.S. 1950. The Ants of North America. Bulletin of the Museum of Comparative Zoology 104. 585 p.

Smith, M.R. 1965. House-infesting ants of the eastern United States: their recognition, biology, and economic importance. USDA Tech. Bull. 1326. 105 p.

Trager, J.C. 1984. A revision of the genus Paratrechina (Hymenoptera: Formicidae) of the continental United States. Sociobiology 9: 51-162.