Surface applications of pesticides are never going to work well on something that can burrow inside your plants. BT affects them, but again, it has to be eaten to kill them, and if they're eating the inside of a cucumber, they won't eat it. On the other hand, you can still get the ones on the surface with it.

Pickleworms KILLED me last year. From the entire blasted garden, I only got one zucchini. That was it. I hate them, I hate them, I hate them. Yes, I'm still bitter. :)

I completely feel your pain.

I don't won't to second quess you. but I think you need to reinvestigate. Pickle worms do not live over winter, they will survive mild winters in zone 8b and 9. Since they do not over winter in 8a or above they do not show up until usually first week in July for me in Central SC NW OF Columbia. Pickel worm is the larvae of a moth, it lays it eggs only on fruit and not on the plants. Pickle worms do not kill the plants they only destroy the fuit. You can see pickle worm damage by what looks like saw dust on the fruit and small holes. Summer squash especially and pumpkins, then they work on down the cucurbit family, but prefer the Squash members of the Cucurbits. Best control and it is organic, I am a certified organic grower, is to mix safer soap or M-ped with Dipel soluble powder (BT) and spray the base (root area of the plant) for cucumber beetles and squash bugs and spray only the fruit for pickle worm control. Must repeat every 7-10days.
I would think your problem is Cucumber beetles. These small green and black striped or spotted beetles feed on a wide aray of plants and can quickly kill squash ,cucumbers melon. The adults will chew up small seedlings best control is row covers till blooms start. The main cause of death to the plant is the larvae of the cucumber beetle. The beetles only lay their eggs at the base (root) of the plant. do not apply mulch around base of squash plants keep this area clear for about a foot away. The squash bugs like to hide during the day along with the cucumber beetle so removing mulches next to squash eliminates hiding places. Next since all squash bugs hide at base of plant during heat of day and all cucumber beetles lay their eggs at the soil line at the base of the plant spraying with safer soap and Dipel (BT) at the base, will kill adult squash bugs and any cucmber beetle adults mating and laying at the base of the plant. The Dipel(BT) will then kill the maggots of the cucumber beettle that are feeding on the roots of the plant. This feeding on the roots by the cucumber beetle larvae is what causes a perfectly healthy looking plant to suddenly wilt then die. The only effective way to combat cucumber beetles is a spray program every 7-10 days at the base only of the plant since sprayng the whole plant is a waste of spray and the soap will kill any insect it comes in contact with even benificials. And only sprary late morning when it is hot and sunny when bees are not present and since this is when the squash bugs are hiding at the base of the plant also. There is also very effective lures and sticky traps for cucumber beetle control and monitoring. I use all of them. I make my own sticky traps and lures and I spray weekly with safe organic controls and I have nice clean healthy plants. Rodger

Thanks, everybody. At least I don't feel singled out any more. Rodger, they are pickleworms. I looked them up in Whitney Cranshaw's excellent reference, Garden Insects of North America. The caterpillars were translucent with four rows of tiny black dots and reddish heads, about a half-inch long. Besides, my plants are fine, just no cukes I'd want to eat. Karen, my husband and I cut up the holey fruits, extracted all the worms and dispatched them individually, apologising all the way, then composted the remains. Ribbit, I guess it's just nature and we're stuck with it.