Responses of Striped Earwigs Following Applications of Heptachlor and Mirex, and Predator-Prey Relationships Between Imported Fire Ants and Striped Earwigs1

Abstract

Field populations of striped earwigs Labidura riparia (Pallas) in Baton Rouge are resistant to chlorinated hydrocarbon insecticides and are not killed by these chemicals at rates recommended for control of imported fire ants, Solenapsis saevissima richteri Forel. Striped earwig populations developed to a significant higher level in suburban yards treated with 10% granular heptachlor than in untreated yards. Heptachlor-treated field plots covering 2800 square feet developed higher populations of striped earwigs than did either mirex-treated (0.025% bait) or untreated field plots of equal size. Heptachlor-treated field plots situated 100 or more feet from suburban yards had significantly fewer earwigs than did heptachlor-treated suburban yards. Imported lire ants and thief ants, S. molesta (Say), were the only predators observed feeding on eggs of the striped earwig when eggs were exposed overnight in 0.5-dr vials situated in untreated field plots. Within heptachlor-treated field plots where fire ant populations were reduced to a minimum, cannibalism by 5th and 6th instar and adult earwigs on eggs of their own species was frequently observed.