It is that time of year for us to begin scouting for squash vine borers. The adult vine borer is a moth. The moth is orange and black and it flies in the daytime. Some folks think that it is a wasp, as it appears to be stinging the squash vine as it deposits its eggs on the stems. Once the eggs hatch, the larvae bore into the vine and cut off the flow of nutrients to the plant. Plants that look good this evening are completely wilted tomorrow. If caught in time, the stem can be slit open long ways and the white worm-like larvae removed. Put some dirt over the stem and the plant may recover.
If not found in time, the plant will die and the larvae will complete its life cycle by coming out and boring into the soil. Here, it forms a small cocoon-like structure, which will produce the adult moth. Our season is long enough to produce two batches of moths. Never throw wilted squash plants into the compost pile, as this will provide a place for next season’s moths.
Photo 2: Vine borer larvae. Special image
When you see the moth flying around the squash, the problem is about to begin. The moth is very fast and agile, but if you watch closely, you can find them resting on a leaf. This is where you can test your reflexes and swat them with one hand above and the other below the leaf. A sweep net can also work to capture them as they try to fly off. We were able to eliminate the threat in the community garden last year using this method. You will destroy a leaf or two but it is worth it if you eliminate the moth. For those of us who are less quick, the moths will rest on the leaves at night and a fly swatter can work.
When inspecting the plants, if you see small brown dots on the stem, this is most likely the eggs from the vine borer moth. These eggs can be wiped off with a damp cloth. For those who wish to spray, products containing bifenthrin can be effective. Sprays should be directed toward the base of the plant and applied in late evening to prevent the killing of honeybees.
I realize that some people have quit trying to grow squash due to the vine borer problems, but with a little understanding of the vine borer coupled with swift action, you can successfully grow squash.
