I came home from shopping this morning to find my mesquite tree covered with these. I was filling the bird feeders when I first noticed them. It took a minute for it to register how many there were and then, to realize that they are devouring my velvet mesquite tree. I don't have any pesticides around the house because I refuse to use them . I don't want to poison my birds. I decided to try to wash them off the tree, so I grabbed the hose and sprayed away. Well, the hose knocked them off, but they just started crawling up the trunk again in hoards. There had to be at least a thousand of these pests, and they have already eaten the tender new leaves off the tree. I am afraid it will be denuded by evening.
Update from Doug Taron:
Hi Kathie- I may not be able to ID your beetles myself, but I do have contacts. This is from my friend John who I was just collecting out in Colorado with:"They are spotted blister beetles, Epicauta sp., and they congregate like that during mating season. They will feed on the foliage and flowers but shouldn't defoliate the trees. They do more good than harm as the larvae are grasshopper egg predators/parasitoids and adults often are pollinators. Of course it goes without saying that she should not pick any of them up if she is highly sensitive to dermatitis since blister beetles are called that for a reason - their hemolymph contains strong irritants that will cause such." Wed Jun 25, 07:49:00 AM 2008