Target Life Stages:
Larvicides are products that kill an insect’s larval stage. For CM, the window of opportunity to kill the larva is very short, after it has hatched and as it attempts to enter the fruit. Most CM eggs are deposited on leaves of fruiting clusters or directly on fruit. A CM larva hatching from an egg placed on a leaf has the ability to find a fruit and enter it within a few hours. Traditional insecticides (Guthion, Imidan, Sevin, Warrior, Danitol and Asana) are highly toxic by contact. That is, a CM larva can be killed by just walking across residues of these products. The newer insecticides (Assail, Calypso, Intrepid, Rimon and Proclaim) have very little contact activity. Their main effect comes when the CM larva consumes the insecticide as it attempts to enter the fruit. Some of these products allow more “stings” (shallow, unsuccessful entries) than traditional insecticides because the CM larva does not die until after it has partially or completely entered the fruit. This weakness is more of a problem in the second CM generation when scars left by “stings” are more evident.