Just hatched mass of caterpillars, a.k.a. armyworms? The black stuff looks like frass (droppings).

They drop from leaves from a strand of silk when disturbed - did you check the undersides of the leaves?

I did check and didn't see worms, but the leaves are skeletenized so I think you're right. I sprayed with Neem oil. Any other suggestions? Thank yoU!

Hi suziluvv,

Your use of Neem Oil suggests that you are an Organic Gardener. If that is the case, there are a lot of things that I couldn't expect you to use. Incidentally, did you know that Neem Oil is illegal in the United Kingdom ? (that is a clickable link)

ZM

I did not know that about Neem! Thanks for letting me know. And I will pull the zinnia. I'm a first time gardener and am learning so much!

IMPE, there are always some that survive and move on to other plants. Check the base of the plants, as they will often curl up and hide there. They can grow to a couple of inches long, but as you can see in the photos I posted, they start out very very tiny, and some will hide on the undersides of the leaves alongside the veins, and blend in, making them difficult to spot.

I just smoosh 'em with my fingers when they're small like that.

Hope this helps - good luck 🙂

Those tiny worms are the food for many beautiful baby song birds. If you have just one effected plant, leave it be and let nature do its thing. If you can’t stand the look of it, pull it and throw it behind your garage.

Interesting point. I sometimes pick caterpillars off plants and leave them out on the sidewalk or driveway for other animals to eat. Our anole lizards will come running out and snatch them.

I do the same with grubs.

Is there a tree nearby that has caterpillar webs in it? I had this issue with some roses last year and it was because of caterpillar webs in a nearby tree. I treated the tree and the problem was handled. I won't get into treatments, but find something that you are comfortable usiing.

I might be having same problem. Something eating my zinnias. And agastache and monarda. This morning I saw black dots smaller than poppy seed under the monarda leaves. It looks similar to your photo. But I dont see any caterpillars or ants. It’s so frustrating.

I think flea beetles can do similar damage.

Sometimes the caterpillars have already been eaten by predators - or they drop off the plant to the ground and crawl away, or burrow into the soil to pupate.

I believe the rule of thumb is healthy plants can lose up to about 1/3 of their foliage and still be OK, so if damage is to less than 1/3 they'll likely survive.