Effects on Nontarget Arthropods of Malathion Bait Sprays Used in California to Eradicate the Mediterranean Fruit Fly, Ceratitis capitata (Wiedemann) (Dystera: Tephritidae)

Evidence of bait attraction, direct kill, and population reduction of nontarget arthropods was obtained by comparing gardens in two Malathion bait-sprayed sites with those in an untreated city and an unsprayed natural area. A variety of polyphagous and carnivorous arthropods were attracted by the baits, and in most cases fewer numbers were caught in treated than in control areas. Some phytophagous insects (Homoptera, Apidae, and Lepidoptera) apparently maintained or increased their populations during or after the spray period. Populations of calypterate muscoid flies were probably unaffected by the sprays.