Probably baby grasshoppers. If they consume everything on the plant they are grasshoppers.

One year upNorth, I had a zillion of these. In June. I had a flat of
blue eyed star grass I had started from seed--a long process, on the dock that was about 4in high. It was windy so when we went to town for food, I moved them down to the gravel. (things tend to blow off). We were just gone an hour or so, and when we got back, all gone. Eaten down to nothing. I was so mad.... we looked carefully around, and yep there were tiny grasshoppers everywhere. We used to have zillions. One reason there were never flowers along the shore, I suspect.

So I checked some catalogs and found a natural deterrent. It was a spore mold made at a university to sterilize the adults so they wouldn't propagate! It worked, but took 3 seasons and now this product is banned in my state even! We have no grasshoppers around our house tho. Down the way on the shore there are as many as ever, but we are spared. They must be quite territorial or something.

Until the product took hold I would walk around and pinch them off. Larger ones I'd hit with a fly swatter and stunning them and then squash with a rock (they are difficult to kill out right).

The ones mating were my target...since occupied this way they were slower to sail off. Many start off green and then change color when they grow up. I also learned that grasshoppers are cannibals, and the large ones eat the smaller. Our late Tippy used to hunt them which I encouraged!

I think the Basil is just tender and yummy. And went first.

It was about 5 yrs of grasshopper frenzy... but now it is gone and I have wildflowers along the shore again!

Here is a Google search for "grasshopper nymph"
http://www.google.com/search?q=grass...w=1173&bih=743

And yes when first hatched out they are really small, and difficult to see.