Yep, squash bugs, and not only will they eat your plants, their piercings bring on disease faster. The bane of squash, along with vine borers. Best thing to do is prevent them to begin with - not so easy - but many use row covers, etc. That's too late for you. Pick as many as possible, also looking for the coppery colored eggs on the undersides of leaves, and squash them. Since squash flowers are such a huge attraction to bees of all sorts, I'm reluctant to put anything on the plants that could harm the bees. This year I've planted marigolds in the hills with my squash, and I've been cutting fronds of tansy and putting it in and on my squash plants. I haven't been hit yet, but I think the key is responding fast when you do see them. I've also planted the Tromboncini (I think that is it) type of squash this year, which I've been lead to believe is more resistant or undesirable to the traditional squash pests. I'll believe it when I see it!!

Tangerine, here's a good fact sheet about your squash bugs. A significant infestation would be a good time to mix a small amount of horticultural oil and try to coat the stems and under the leaves where you see them. The eggs and nymphs are quite sensitive to the oil. I don't recommend that you spray over the top of a plant in the summer, just where you see eggs and lurking insects.

But if you read the fact sheet, you'll learn that the most important aspect of controlling squash bugs has to do with general housekeeping tasks....removal of all garden debris at the end of the season, etc. Some post- and pre-season garden work on your part can reduce the SB population to practically nothing.

By the way, great picture!

thank you for the help! Can I still eat my zucchini if some horticultural oil gets on it or should I do a round of harvesting first?

lots of great info above -- I will just add that I find that adding a little Palmolive dishwashing liquid to a spray bottle of water and spraying them kills them in moments. It's fun. Hopefully someone will let us know if there is anything bad about using Palmolive in the garden, but of course it rinses easily off the zucchini.

Also, to get the eggs off the bottom sides of the leaves I used to find difficult, until I saw a tip on here to wrap duct tape around your hand sticky side out and take them off with that. Also fun.

BTW, they are in the stink bug family and they will stink when you squash them. That's why I'd rather spray.

I will second what rhizo said about garden housekeeping. I've reduced the SB population in my garden significantly by bagging all summer squash plants and debris.

My husband grows spearmint plants in pots around his squash and really thinks that it helps.....he just read it somewhere and has tried it for several years.

I would second Elisa's advice, re: use of a soap spray. Provided that they are completely covered, both adults & nymphs are very susceptible, and perish within a minute or two. There are several formulations that can be used, but I recommend the use of a mild soap, such as baby shampoo, or Safers insecticidal soap. I add rubbing alcohol to my mix, it paralyzes insects briefly, to allow the soap to work. This even seems to kill the eggs.

The nymphs tend to cluster together, so you can wipe out large numbers quickly. But if you know there are squash bugs in your area, the best solution is to watch for & kill the first adults, then search under leaves for any egg masses. The first adults often can be found close to the ground, near the stem, or under leaves which touch the ground. I've noticed that cucumber beetles can be an early indicator, they tend to swarm on plants that are already weakened by adult squash bugs.

Unless you use Safers in your spray, it is best to hose off the plants after the bugs are dead, to avoid damage to foliage.

Oh, and the soap/alcohol spray is also a good way of killing ants & wasps in the home... and it wipes clean. ;-) I use it to kill paper wasps when they build nests in dangerous locations... spray the nest at night, when all of the adults will be present on the nest.

A high-volume spray bottle is best for applying soap spray, such as those sold in farm & fleet stores ("horse sprayers").

Tangerine, I've never seen a horticultural oil that couldn't be used up to the day of harvest. Just give a wash in warm water or in some vinegar to rinse it off.