Well, there's at least 400,000 kinds of beetles in the world. (Some say at least a million, and others say there could be as many as 100 million different kinds.....) I won't pretend that I can guess which one is eating your plants, but it is probable that they are blister beetles. Blister beetles come in many colors, from solid colors to bi-colors, etc. Some are solid black, some are black and brown, black and red, black and orange, etc. So. blister beetles would be my first guess, but there's at least tens of thousands of other kinds it could be.

Since you're seeing frass, you may have some kind of caterpillars as well....could be hornworms, but could be tomato fruitworms, army worms, or practically any other caterpillar in the world.

With the beetles, I prefer to handpick them and destroy them. I usually put on disposable latex medical gloves (you can buy them on the aisle at big box stores where band-aids are usually sold...one box lasts me all summer) and carry a bowl of soapy water to the garden with me. I hold the bowl under the plant and knock the beetles off the plant into the soapy water where they drown. If the beetles are fast and are moving around and hiding, I try to grab them with my fingers and drop them into the bowl. Or, if I have scissors in my hands and am deadheading flowers, sometimes I just use my garden scissors to snip the blister beetles right in half.

Unless blister beetles are doing major damage, though, I leave them alone because they eat grasshopper eggs. If you kill off all the blister beetles in any given summer, you're likely to have more grasshopper issues the following year because you didn't have the blister beetles around in mid-summer through fall to eat the grasshopper eggs. Still, when blister beetles (or any other beetle) are doing substantial damage to plants, you really have no choice except to do something to control them because they can literally destroy every single leaf, which will kill your plants.

Sometimes when you see caterpillar frass but aren't seeing the caterpillars, you can find them hard at work at night by going out to the garden with a flashlight. If you feel positive it is caterpillar frass, you can spray your plants with a Bt caterpillar killer and it will kill them after they ingest leaves from the sprayed plants. It takes a day or two to kill them, but they stop eating leaves shortly after ingesting it. If you choose to use Bt, try to put it on the foliage but to keep it off the actual flowers because it kills butterflies and moths, many of which are desirable garden companions.

You might be able to successfully kill blister beetles with a pesticide, but I don't use a pesticide on them because any pesticide that would kill them also would kill many beneficial garden insects too. Spinosad is a broad-spectrum organic pesticide that likely would halt the damage on your eggplants, but I use Spinosad very sparingly since it kills a broad spectrum of pests. You could, for example, use it only on your eggplant plants and not on anything else. At least that way, the beneficial insects in your garden wouldn't suffer unless they were on the eggplant plants. You also could spray your eggplant plants with a less strong organic insecticide like insecticidal soap, neem or pyrethrin (don't use the last one if you have pet cats).

Dawn

Thank you for the information Dawn. I googled blister beetles and it does look like that is the pest. I am loathed to use any chemicals in the garden, as we have managed to garden as organically as we could so far. I guess I will just keep hand picking them. The ones I removed today in the method you described, a bucket of soapy water and gardening gloves. I didn't realize they could cause blisters, I am going to be more careful about wearing gloves out there form now on.

We found one hornworm yesterday on a tomato plant and removed it (permanently), but since we found one I am guessing that means we have more and just could not find them yet. I will check again later.

I am mostly mad because my eggplants were the thing that was growing the best! They had not been bothered by rain, high temps. any pests... nothing. I should have known that couldn't last!

You're welcome.

It was an easy guess because in my garden blister beetles devour the leaves on several plants....tomatoes, cucumbers and beans, generally,....and they usually show up about now.

I'm glad we were able to figure it out.

Your eggplants should be fine. Eggplants are incredibly resilient plants and can overcome a massive amount of pest damage once they are well-established. The hardest time for them is when flea beetles hit them hard early in the season when they are still fairly small and not yet well-established.

Just keep an eye on your plants. If it seems like their growth has stalled and they are struggling to overcome the blister beetle and caterpillar damage, pamper them by feeding them with a good water-soluable plant food. They respond really well to either fish emulsion or liquid seaweed or to a combination product that contains both liquid seaweed and liquid fish emulsion.

The only other reason that eggplants might stall would be if you leave an eggplant fruit on them too long and it gets overripe, which sends a signal to the plant to stop making more fruit. So, be sure to keep the fruit harvested.

I generally don't grow eggplant very often because no one in my family will eat it, but I grew it for a few years and gave the fruit to fruit to friends who didn't have a garden back then. It tolerated heat and drought in my garden even better than tomatoes and peppers do, so usually you won't have trouble with it in the summertime, other than a few random pests. I think your plants will recover and will be just fine.