Yes, these are "locally common" insects that are sometimes abundant in a small area, for a short period of time. You could probably go for miles before you see another one, but there would be many....Yes, they are poisonous. They secrete a potent defensive chemical (cantharidin) from their body joints if squeezed. The chemical can raise painful, scarring blisters on sensitive skin. Ingested, the insect can be lethal, so keep curious kids from sampling one. Same goes for pets. I believe the larvae of these beetles are parasitic on other insects, but I'm not positive. Adults will eat foliage, and sometimes cause severe damage to plants in areas where the beetles are numerous.