For the past eight years, ARS entomologist Bob Pfan-nenstiel and other ARS scientists have been studying the feeding habits of these nocturnally active predators in the Lower Rio Grande Valley in South Texas.

The researchers at the ARS Beneficial Insects Research Unit (BIRU) in Weslaco have conducted day and night field tests on insects that feed on the eggs of lepidopteran in-sects such as Helicoverpa zea (the cotton bollworm/corn earworm) and Spodoptera exi-gua (the beet armyworm).

The predators that feed on the eggs during the day are very different from those that feed at night, and nighttime predation can be much more important.

Two nocturnal predators have stood out from the rest: cursorial (running) spiders, mainly the species Hibana futilis, and the exotic Asian cockroach (Blattella asahinai).

Cursorial spiders consume significant numbers of moth eggs in row crop foliage, with about 99 percent of their predation occurring after dark.

These spiders are particularly important in cotton, where they benefit from consuming the plant's sugars. Since 2006, when the exotic Asian cockroach reached South Texas, it has been the most important late-season predator of lepidopteran eggs in soybeans.

Laboratory and greenhouse studies by BIRU scientists, including Shoil Greenberg and Randy Coleman, have shown that the spiders prey on other cotton pests, including the cotton fleahopper, Pseudatomoscelis seriatus, and the cotton plant bug, Creontiades signatus.