Squash Vine Borer
Squash vine borers (SVB) are day-flying moths, with bright orange markings on their backs and legs. They resemble wasps. Most eggs are laid on the stem within a foot of the soil. Hatching larvae tunnel into the stem and, if plentiful, cause wilting, reduce squash yields or even sever the stem from the roots. In rare cases when populations are very high, larvae may bore into fruit. The large cream-colored larvae are 1 to 1 1/2” long and 3/8” wide.
The pupae survives the winter 1 or 2” deep in the soil. Spring or fall plowing buries pupae deep in the soil and reduces populations. Preferred hosts have thick stems, while thin stemmed squash tend to be more resistant to attack. Yields of summer squash can be reduced by 1/3 if infestations exceed 5 larvae per plant.
Pumpkins can sustain high infestations without yield reductions. Butternut squash are resistant to SVB.
Monitor with a Scentry Heliothis pheromone trap from early June through early August. Make 2 to 4 weekly applications if more than 5 moths per week are captured. Timing is very important. Treat base of stems thoroughly to target hatching larvae. Some selective materials, such as spinosad (SpinTor or Entrust), provide excellent control of hatching SVB larvae.
Identifying and Enhancing Natural Enemies in Vegetable Crops
Insects
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