Sounds like a pollination problem. These days, especially in some places, there seems to be a dearth of pollinators. Here's a link to a discussion on hand pollination. Just to get fruit, one would not have to tape the flowers shut at all. Simply use the stamen (pollen bearing part) from a male flower to pollinate the pistil (pollen receiving part) or a female flower. If it's a pollination issue you'll start getting fruit to mature.

George
Tahlequah, OK

Here is a link that might be useful: Hand pollination of Squash

I agree with George that it could be a lack of pollinator activity. It also could just be the heat too.

I'm seeing plenty of pollintors here at our house, but only very early in the mornings. By 9 a.m., nothing much is buzzing around except the dragonflies.

If you are seeing bees and other pollinators, then likely your pollination issues are occurring because of the extreme heat.

When pollen is released from the anthers, the environmental conditions can affect it in such a way that the pollen is no longer viable by the time it reaches the stigma of the flowers of the same species. This can occur both during periods of high heat/low humidity and high heat/high humidity.

If the temperatures are too high, the pollen can quickly become denatured.

If the relative humidity is too low, the pollen can become dessicated.

If the relative humidity is too high, the pollen of some plants can become too 'sticky' which makes it hard for it to leave the anthers. That happens a lot with tomatoes, but I don't know if it happens with squash.

If the winds are consistently above 15 mph, the pollinators often are less active.

If (don't we wish this were the case now) the weather is too cool and too rainy, the pollinators can be less active.

If you follow George's instruction and hand-pollinate, you'll get squash and pumpkins, assuming the heat or humidity haven't made the pollen non-viable. Also, be sure the plants are not drought-stressed. If they are too dry, they'll sometimes abort the small squashes after they pollinate because the plants "think" or "know" that they are too stressed to carry and mature the fruit.

Dawn

Thanks! I'll try the hand pollination method. We have plenty of bugs here and my gardens are on a sprinkler system so I'll assume it's the heat.

I agree with Dawn, think it's the heat, because I have witnessed lots of honey bees and bumble bees on my pumpkin flowers. Still the little fruits shrivel and die when they're about 2" long. I guess even the curcubits can't take this heat!

Susan