Lately a lot of people have been asking questions about Squash Bugs and their zucchini. I thought I'd post the recommendations from Utah State on how to deal with these annoying buggers.
Most people ask what to spray, but the thing to keep in mind is that insecticides are not really effective against these pests. According to USU:
Squash bugs are very difficult to control. Insecticides are not very effective, but if insecticides are used they work best against the very young nymphs.What we have been doing this year which seems very effective is going out to the garden most evenings and looking for squash bugs and their eggs. We usually find several adults and quite a few eggs. Killing the adults is pretty easy as they are slow enough that you can grab them and they are easy to squish. Eggs are pretty easy to spot and we simply make a point of smashing the eggs.
- If you plan to use insecticides, sprays should be applied when small nymphs are present, which generally occurs early in the season.
- Before spraying, check plants carefully to make certain that small nymphs are present. Squash bugs hide on the underside of leaves or down near the base of the plant.
- Nonchemical methods of control are usually as effective as insecticides. Serious attack by squash bugs can be avoided by planting sensitive varieties early so harvest is complete by early August.
- Once harvest is complete, remove the squash plants from garden. Plants left in the garden allow the bugs to build up to higher numbers, which will lead to greater problems the following year.
- Plant varieties of squash that are less sensitive to the bugs. Zucchini seems to be the variety most sensitive to attack by squash bugs. Other summer varieties and most winter varieties seem better able to tolerate feeding by squash bugs.
- Squash bugs are active during the day. At night the bugs hide under boards or other objects. This behavior can be used against them in small scale plantings such as gardens. Place boards near the plants (between rows or around the garden edge) and early every morning turn them over and squish all the bugs you find.
- Squash bugs also seek out sites like wood piles or sheds to spend the winter. Large numbers of bugs overwintering in these sites can lead to high numbers of bugs in your garden the following year.
When we first started we would find several dozen clusters of eggs each night. But now a couple of weeks after our squash bug genocide began we only find one or two clusters a night.
If you already have many many squash bugs and egg clusters that have hatched you may consider spraying. These are the recommended insecticides for home owners: Ace Dust, Bayer Advanced Dust, or Bonide Eight.
For more information check out the USU fact sheet on Squash Bugs