Squash vine borer larvae are white with brown heads and about 2.5 cm long.
Squash vine borer larva (left)-Alabama Farmers Cooperative Inc, Larvae (right)-Kansas State University
The adult is clear-winged moth resembling a wasp. They are orange and black and have black stripes on their bodies.
Moth (left)-Kansas State University, Moth (right)-Ohio State University
Habitat & Lifecycle
These pest are found east of the rocky mountains in the US and Canada. They overwinter in a cocoon in the soil. Adult moths lay their eggs along the stems and the eggs are small and brown or reddish. Moths lay their eggs in early spring. There may be up to two generations per year depending on climate. A very cold winter can kill off many of the cocoons.
Lifecycle (left)-North Carolina State University, Damage from the squash vine borer (right)-Ohio State University
Diet & Damage
They bore into the stems of cucumbers, squash, pumpkins and other gourd type plants. You can see a small entry hole where the larvae go inside the stems to do the most damage. The vines will wilt and eventually die. You can tell if they are present since they leave a small mass of green debris just under the holes. Squash stalk borers are extremely hard to control. It is critical to stop them from entering the vine since once they are in there it is too late.
1) Nema-JectTM Nematodes – Nematodes injected into the stems helps control theses worms. This method is convenient with container, greenhouse or house plants.
2) Floating Row Covers – In the spring when the plants are newly planted, use row covers so the moths cannot lay their eggs. If you use a row cover then you must pollinate the flowers by hand.
3) Hand Pick – Try to catch them in egg stage so you can kill them before major damage. If you see the holes, take a sharp knife and slit the stem to remove the worms. Bury the injured section of the plant. This will help the injured section to reroot.
4) Crop Rotation – Rotate your crops from year to year and plant the cucurbits type plants far from where they were planted the previous year.
5) Plant Resistant Varieties – Butternut squash, acorn squash and some zuchinni varieties.