Yellow Crazy Ant

The yellow crazy ant got its name from the way the workers run about in search of food. The scientific name is Anoplolepis gracilipes (Forel). The workers are yellowish brown with a dark abdomen. They are about 1/8″ to 3/16″ long. The workers have very long legs and very long antennae. These ants resemble the crazy ants that are common in the southern United States, however they are only distant relatives.

Scientists are not certain where yellow crazy ants originated. They are found in tropical areas including Australia, Hawaii, Okinawa, and some Caribbean islands.

Yellow crazy ants live in very large colonies with multiple queens. The workers gather nectar from plants. They also care for plant-feeding insects that produce honeydew.

Because the colonies have multiple queens, they are able to create new colonies very easily. Fertilized queens, accompanied by some workers, simply walk away from the nest. They find a place to make a nest and they start new colonies. The new colonies cooperate with the original colony. The workers are not aggressive toward the workers of neighboring colonies.

Because there are multiple queens, it is easy for colonies of yellow crazy ants to be transported by people. Ants can be carried in shipments of agricultural products, household goods, or even in luggage. If a queen is among the ants that are transported, a new colony can be created at the new location.

Christmas Island, an island in the Indian Ocean, has a tropical climate. Most of the island is covered by rain forests. The yellow crazy ants were accidentally brought into Christmas Island in the early 20th century. The ants had a dramatic impact on the environment of the island.

The yellow crazy ants reduced the population of red ground crabs in the areas where the ants lived. This allowed the growth of seedlings that had previously been controlled by the crabs. The ants encouraged the growth of scale insects, which feed on plant sap. The increase in scale insects killed leaves and even entire trees. The ants attacked birds and animals and scientists believe they changed the makeup of the bird and animal population on the island.