Squash Vine Borers
Identification
Squash vine borers are small fat white caterpillars about 1 inch long;
they are the larval form of a large moth that is black and orange with
clear wings. These worms will attack primarily squash and pumpkins and
occasionally cucumber and melon vines. The adult female moth lays eggs
on the vines in June and July. The larva will then emerge and bore tunnels
in the plant's stems to feed for 4 to 6 weeks while disrupting the flow
of water and nutrients in the plant. Yellowish-green excrement or insect
frass is very evident around the holes created by the borers. Most severely
damaged plants will wilt and collapse and eventually die.
Prevention and Control
There are a few ways to prevent squash vine borers. Floating row covers
are really the only way to prevent the moth from laying eggs on the vines.
But be sure to remove the covers when the flowers bloom to allow pollination
by insects. Crop rotation and early planting might help too, since these
borers overwinter in the garden soil and debris. Once the plants get up
in size, dust or spray the vines with an insecticide such as Malathion
or Sevin every 7 to 10 days. Unfortunately, insecticides will not work
once the borer has tunneled into the plant. Slitting the damaged vine near
the holes and frass and then removing and killing the borer might help
save the plant. If time allows and all things fail, replanting is always
an option. |