Squash vine borer can be killed by chemicals but the trick is in the
timing of the application. An insecticide is effective when applied at
the time that eggs are hatching. A preventive treatment regime is to
apply an insecticide when vines begin to run, and re-apply every 7 to
10 days for 3 to 5 weeks. The application should be directed to the
base of plants, at crowns and runners.
Chemicals used for borer control in gardens are methoxychlor, rotenone,
pyrethrum, malathion, or carbaryl (Sevin), applied as sprays or dusts.
Restricted-use insecticides used for borer control by commercial
growers include endosulfan (Thiodan) and pyrethroids (Ambush, Asana,
Pounce). The biological insecticide BT, in the forms currently
available, is not effective because it cannot be applied to the plant
parts that are eaten by the borer.