Ever wonder at the difference between locusts and grasshoppers? I did, so I asked (Ask.com). Turns out, not much. Physically, you can't tell them apart. Locusts are known for having a swarming phase, usually distinct morphologically. Many locusts are now known to be just the swarming phase of a previously presumed different species. And some grasshopper species sometime engage in gregarious (swarming) behavior.
So far, no swarming. Lucky me.