Thief Ant

Pronunciation

How to pronounce Solenopsis molesta: /ˌsoʊ͡lɛˈnɒpsɪs məˈlɛstə/

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Summary

Solenopsis molesta, commonly known as the thief ant or grease ant, is a small, widely distributed ant species in North America that is known for nesting close to other ant colonies and feeding on their brood and various food sources. They have a unique biological and behavioral adaptation to scavenging, making them a common pest in residential areas.

Physical Characteristics

Workers range from 1.4-1.5 mm, males 3.5 mm, queens 3.5-4+ mm depending on the state of physogastry. Queens are yellow to light brown, workers are yellow to pale brown, with very small eyes and covered in erect and sub-erect yellow hairs. A two-segmented petiole connects the abdomen to the thorax, and they possess small stingers on their oblong abdomens.

Identification Tips

Solenopsis molesta can be distinguished by their yellow coloration, small size, and the presence of small stingers. They have a two-segmented petiole and 10-segmented antennae ending in large segmented clubs.

Habitat

Moist soil in various locations, especially in sunny spots. Commonly nests in mounds of other ants, in exposed soil, under rocks, or rotting logs, and can even inhabit cracks in residential homes.

Distribution

Native to the United States, found in Eastern, Western, and Central parts of the country, as well as northern Mexico.

Diet

Generalist scavenger; primarily feeds on grease, meat, cheese, other dairy products, seeds, and larvae/pupae of other ants and insects. Not attracted to sweets but may consume fruits and sugary soft drinks.

Life Cycle

Nuptial flights occur from late July through early fall. Queens can lay between 27 and 387 eggs per day with an average of 105, taking about 52 days for an egg to develop into a fully mobile worker. Young spend about 21 days in the larval stage when weather permits.

Reproduction

Mating occurs from July to late fall with queens and drones flying. Colonies may be polygynous, sometimes having up to eight queens.

Ecosystem Role

As scavengers, they contribute to the ecosystem by breaking down organic matter and recycling nutrients.

Economic Impact

Can be a nuisance in homes due to their small size and ability to enter sealed food packages, making control difficult.

Health Concerns

Known to infest food supplies; not medically significant but can cause annoyance and food contamination.

Similar Taxa

• Pharaoh ant (Monomorium pharaonis)

Misconceptions

Often confused with pharaoh ants due to size and markings. They are commonly mistaken for being attracted to sweets, which they are not.

Tags

• Thief Ant
• Solenopsis molesta
• Pest Ants
• Scavenger Ants
• Ant Identification