Hi Theresa,

I believe those are both squash vine borer. The boring into the stem is definitely squash vine borer. The larva on the fruit also looks like a tiny vine borer larva. They can bore into fruit (though I've not seen it!). Pickleworm is a southern pest, so if you are down south it could be possible.

Squash vine borer typically does not bother cucumbers, it mostly bothers squash and pumpkin, so your cucumbers should not be at risk.

There is not much to be done if the caterpillars are in the stems or fruit! There is only one generation of this pest, though, so any plants that weather the storm should be okay and produce (there are not additional generations that will keep emerging to cause more and more damage). 



This is a nice publication on organic controls for squash vine borer. These include row covers to keep the moths off of plants, so they can't lay eggs, and insecticides (e.g. spinosad) applied before eggs hatch and caterpillars enter stems/fruit (the eggs are laid on the surface of stems, caterpillars hatch and if there is insecticide will die). If you are still seeing moths flying (they are out in the day), you could try to protect healthy plants, but I would guess it is too late to do much good (time/money with little result).

Row covers are effective but have to be on before the moths arrive to lay eggs, and need to be removed for pollination. There are some organic insecticides, but these need to be applied BEFORE the eggs hatch into caterpillars, that then move into the plants where you cannot reach them.

Make sure to work the crop under promptly whenever you finish harvest, or are done with it. You may be able to kill some larvae that way before they complete development (which would reduce the number of moths emerging next year).

This is a tough pest when land is scarce and cucurbits need to be grown every year within a confined area! But it is a specialist on cucurbits, so if you can rotate out of squash and pumpkin for a year, the problem would be greatly reduced. That is hard to do.

Hope this helps!

Best regards,

Ben Werling

Thank you Ben.

We appreciate your feedback and the additional suggestions. We did decide to clear our fields, since more than 70% of the crop was being affected. We will be rotating out the crops for next season and then incorporating some of the suggestions the following year. Best, Theresa