Timing is crucial. The susceptibility to pesticides is found in the behavior of CBT larvae. During spring and fall months, the larvae are meticulous at cleaning out their galleries and maintaining the frass tube. During this behavior, the exposure to lethal and sub-lethal doses of pesticides happens frequently as larvae visit the outer bark. Recent studies have found that many pyrethroids and other chemical classes persist, at great lengths, in treated wood.
Preliminary findings show a sub-lethal dose from a few of the compounds.
At 1 and 3 week intervals, there is minimal larval mortality. However, most larvae appear to receive a sub-lethal dose. Symptoms include cessation of feeding and severe nerve activity. Eventually, these larvae will lose critical biomass and expire. European literature reports various species of snake flies found preying on CBT larvae inside tunnels.