Have some squash blooming very well, but with no fruit. Add?

Any bees around? Otherwise tickle the stamens with cotton wool bud

If you are using poisons you may be doing in your pollinators. Or your neighbors are. As John stated, you should try to hand pollinate. I am not sure where John is from, but I believe a cotton wool bud is the US's lowly Qtip. Just go from one flower to the next spreading the pollen and see if that works.

Just be sure you tickle the pollen producing pistils of a male blossom first. Squash and related plants have both male and female flowers on the same vine of the plant. Male flowers bloom on longer stems than female blossoms, which bloom relatively close to the plant vine. Related plants include cucumbers, gourds, watermelon, cantaloupe, all varieties of squash.

I may try this on my cucumbers, I haven't seen many bees around this year in my veggie garden, I have more winter squash forming that cucumbers, which is as switch from last year.

I always plan a few rows of flowers to invite pollenators to my garden. That said, once the temperature reaches 90', most veggies will keep flowering but not fruit. It is too hot for them. That's pretty consistent for summer in the south and west US.

http://homeguides.sfgate.com/squash-plants-blooming-but-not-producing-99660.html

Very likely there are female and male plants, and you MUST get cross polination. I have the same problem with yellow crook neck squash.