Our insect of the week for June 30, 2025 is Tabanus atratus Fabricius, 1775 [DIPTERA: Tabanidae], commonly known as the horsefly. It is native to central Illinois and adults are often observed in suburban lawns, grasslands, and forests. Large compound eyes in adults are dichoptic (separated) in females and holoptic (continuous) in males. Mouthparts consist of piercing organs (mandibles with toothlike serrations for cutting flesh, serrated maxillae, median hypopharynx and labrum-epipharynx). The labrum is spongelike and used to lap up spilled blood.

Larvae require moist environments and pass through 6-9 instars. Pupal stage lasts from 1-3 weeks.

Adult horseflies are active during daylight hours and can be quite persistent once they have located a blood meal (perhaps you).

The individual in this stacked photograph was collected by our former member, Gordon Adams during July, 1984 (Peoria Co., IL).