Odorous House Ant (Hymenoptera: Formicidae) Colony Movement in Response to Moisture, Shade, and Food Proximity.

Tapinoma sessile (Say) is a common ant throughout the United States that frequently relocates portions of its nests to form large polydomous colonies in urban areas. Despite widespread research on the control of T. sessile as a nuisance pest, relatively little work has focused on the biology of its nesting behavior and movement. We evaluated shade, moisture, and proximity to food as factors triggering colony movement in laboratory assays. Initially, T. sessile colonies moved to shaded artificial nest sites irrespective of arena moisture. Then, workers and brood were increasingly moved to moist artificial nest sites over time. Colonies moved workers and brood to near-food artificial nest sites over both 1 m and 6 m distances. Queens relocated to near-food nest sites over 1 m distances, but not 6 m distances, during the 49-d study. Results suggest that an increase either in moisture or food in proximity to a residence is likely to account for observed increases in T. sessile abundance near structures.