Your squash plants will be growing great when all of a sudden they are attacked by squash bugs.
Both adult and nymph squash bugs suck the juices from the plant, making the leaves of the pumpkin, squash or other cucurbits turn blackish and die.
At first you may only see a couple of squash bugs, but what you don't see is that they have laid hundreds of eggs.
You need to check on the undersides of all the leaves and get rid of the eggs. You can try to crush the eggs by holding something stiff on on the top side of the leaf and crushing the eggs against it from the underside of the leaf. If you only have a few plants this method will work and you won't need to use any sprays to kill them.
However if squashing bugs and eggs isn't to your liking, or you have more than a couple of plants and more fun things you would rather be doing, you can spray or dust the plants with an insecticide to kill
both the adults and the eggs.
I have found Sevin Garden Dust to be quite effective, but you need to remember that it not only kills the squash bugs but also benificial insects too.
Safer brand Insecticidal Soap is a much better natural alternative. It's a contact killer made from a blend of natural plant sources and pyrethrin oils that come from the chrysanthemum flower. You can use it up until the day of harvest, so it's pretty safe. You will need to apply it every 7-10 days when insects are present or as needed to prevent damage.
Keep an eye out for squash bugs and as soon as one or two show up, get rid of them quickly before they spread. Your squash plant will thank you for it!