This vile horrible creature is the Squash Vine Borer. She’s a wasp mimic, active during the day, a quick flier and most likely the cause of your dying squash. I hate you Squash Vine Borer. She lays her tiny flat orange oval eggs along the stem of the squash, most often where stem meets soil, but sometimes just haphazardly all over. Crazy moth. 7 to 14 days later when her little demon eggs hatch, her filthy disgusting maggoty looking offspring burrow straight into the stem of your beautiful squash plant and devour it from the inside out. At the point of entry you’ll find a hole and frass (poop, looks like sawdust). By this time it’s really too late. After three to six weeks they emerge from the vine and burrow into the soil to pupate. In the south we have two generations per year of these beasts. Glorious.

What can you do if you see the frass and know one has bored into your vine? Some people will cut the vine open, remove the maggot-like larva and bury the vine under soil. I’ve killed the vines when I try this. I’ve read you can inject BT (Bacillus thuringiensis) into the stem but that didn’t work for me either. Could be I did it wrong. Seems like a lot of hassle anyways. I just read people will stick a wire or toothpick in the hole and try to kill the larva that way. I haven’t tried this but it’s worth a shot.

Here are the things we’ve tried. Sister Squid has had the best results by covering the squash with netting and hand pollinating the flowers. After awhile the squash plants get so large they won’t fit under our net anymore and we have to set them free. At this point they usually do okay for awhile before they succumb.

Another tactic is to hunt down the eggs and scrape them from the vines before they hatch. The eggs take anywhere from 7 to 14 days to hatch. So if you went out every 6 days and checked for eggs you should be alright. I’ve used this method and if you have more than a few squash plants it’s a real hassle. I find it hard to check all the vines thoroughly without injuring them. I also tend to miss some eggs.

It helps to bury the squash vine stem as it sprawls out. It will root from the sections that are buried and if a borer takes out a section of vine you might be able to cut that section out without damaging the rest of the plant too badly.

A few sites have suggested aluminum foil under the vines to disorient the moth. Sister Squid tried this and it didn’t seem to work well. Then Squid tried mylar which seemed to work at first but now our squash vines are riddled with borers again.

In our garden we’ve found that the moth has a special taste for yellow crooknecks, zucchini and other Cucurbita pepo. She also goes for pumpkins, winter squash, and to a lesser extent cucumbers, melons and gourds. Butternut squash and other Cucurbita moshata are almost immune because they have a solid stem instead of a hollow stem.

Our plan now is to destroy all the squash vines in our garden tomorrow to keep the borers from maturing, entering our soil and pupating into a second summer generation. We will plant more squash as a trap crop to keep them off our melons and cucumbers. As those trap crops become infested we’ll destroy those plants and borers to keep them from pupating in our soil. Other than the trap crop squash we’ll probably plant only Cucurbita moshata varieties for a season because they seem to be immune due to their solid stems. Doing this we may be able to get rid of our immediately local population of Squash Vine Borers. After that’s done we would only have to worry about a borer flying in from a neighbor’s yard. We don’t have a lot of people gardening around us so it should reduce the number of borers considerably. Then we might be able to grow varieties like yellow crookneck and zucchini as long as we pay close attention and evict the borers as soon as we notice signs of their work.