That is a congregation of STINKBUG nymphs. Leave them alone and they will be the bane of your tomato season when they grow up to become pests... They are NOT my friends.... Assassin bugs do NOT have the black bump on their butts. It's how I remember the bad stinkbug nymps. "BAD Bug Black Butt Bump..." And, the final clue: Stinkbug nymphs assemble in congregations, like they're praying in church over whatever they're destroying at the moment. ASSASSIN bugs travel just like their names. Singular. Solitary. You may see a number of them in your grass, but they put distance between themselves as they patrol. They don't hang out as a gang...They're assassins.... I take care of my assassin bugs. As soon as I get home, I'm gonna snatch up that congregation of stinkbug nymphs I noticed just yesterday, sitting on an eggplant, just like yours. I sneak up on them with a plastic bag, and capture them and that one eggplant, all at once... P.S. The eggplant in your post seems to have grown dull. Pick your eggplants when they are very shiny. Pick them regularly to encourage production. The sooner you pick them, the sooner you'll have new blooms. Remember: "A dull eggplant = a bitter eggplant..." Linda This post was edited by gymgirl2 on Tue, Sep 10, 13 at 16:12

Those look like ticks to me. I would get on this right away, and if you have any pets, check them (and yourself!) thoroughly to make sure no ticks have attached themselves. You can use diatomaceous earth, which when sprinkled on them and in the areas they are crawling in, will pierce their exoskeletons and cause death from dehydration. Or if you want to go the non-organic route, look for a spray that kills ticks and spray it on any you see and around the general area. Any Home Depot or Lowe's or garden center will carry these items.

I keep a tub of killer soap water handy to drop critters into.. It is a mass grave for stinkbugs, harlequins, and leaf footed guys. The leaf footed guys are quick when they are old. I have a mature couple that are eluding me. So I expect to see a bunch of babies soon. stink bugs are easy to grab so are harlequins. Try some soapy water with dawn original soap on the babies. I hear that the parents are susceptible but the babies are more vulnerable. It is worth a try. My hand held vacuum cleaner was worthless for me. True, I got it from Goodwill. The dawn soap spray mixture works almost IMMEDIATELY on coried bugs ( a relative to the stinkbugs) by getting into their breathing apparatus. They take about 15 seconds and then start twitching. The net bags are good for the toms but these bugs also suck the plants and leave a poison that causes decline of the plant if it gets too much.

I'm scoring a point for that ID. If your tomatillo plant is pre-bloom, or the blooms have not been eaten, there seems to be enough greenery to keep the plant going. Horticultural oil sprayed on the plant may prevent feeding; any spray with Spinosad as the active ingredient will be effective and is considered an organic control. If a single plant is being infected, I would try hand-2-hand combat for a few days first, unless you have the above ingredients on hand.