I didn't know I had them, but overnight, they ravaged my tomatillo plant. Fortunately, my tomato, pepper and ground cherry plants are as yet unscathed. I know you can pick them off, but since they do enough damage overnight to destroy a plant, I don't want to risk them spreading.
What is the best course of action? Should I dig up the tomatillo plant to prevent spreading? Is there something I can spray?
I seem to recall reading many years ago that diatomaceous earth which is used in pool filters or something will kill the little suckers. Also if you can find deadly nightshade, which grows all over here in Long Island, NY, and is in the same family as tomatoes, eggplants and potatos but poisonous, turns them on and kills them-after they eat them of course. Or maybe try Rotenone.
I'm guessing you've seen the culprits and thus know they're potato beetles? If you've made a positive ID, there are (at least) a couple of things you can do. Spray with pyrethrin (brand names include Safer, Entire) to whack the existing critters. Pyrethrin will take out some beneficials as well, so you might want to weigh the consequences vs. the frustration you are experiencing.
Squishing the critters is the safest procedure for all (except the bugs), and the hubby -- who's really a mild-mannered, wouldn't hurt a fly type of guy -- seems to enjoy smacking those guys between a couple of rocks. So if you have the time and the stomach for it, that's really a good way to go.
Look under your leaves -- if you actually have potatoes growing somewhere, might check there first -- for eggs, which are yellow and/or larvae, which are pinkish. To take care of them, spray with BTSD, a beneficial microorganism that you can find in good garden centers, or farm-type places like Agway. You can also add stuff to the BTSD solution, like fish emulsion, to strengthen the plants while you're fighting the critters. As always, read the labels or find some knowledgeable store person - they may have newer/better information or products. Also, BTSD loses strength quickly in sunlight, so should be reapplied if/when you notice more chewing (unless you live near me, where we've had about one sunny day in the last two weeks).
Personally, I'd leave the tomatillo plant in place as a sacrifice and/or trap, since they're already making a mess of it. (We sacrifice a bed of eggplants every year to keep the potato beetles off the potatoes and still get a pretty good eggplant yield.) I am sure there are two schools of thought on the topic, though, and you should probably go with your first instinct.
I don't know the extent of damage to your tomatillo plant, but it may recover if the bugs are eliminated....It may not however...If that's the case then remove the plant far from your garden area....Your best course of action is to contact you local garden center/horticulturist and discuss the problem with them...They can best advise you on chemical control for your area.
HTH and Good Luck!