Insect and Spider Identification: CLOSED: striped bugs in large colonies on crepe myrtle, 1 by kwrn1

kwrn1 wrote:
I have these striped bugs on my crepe myrtle and another "barkless" tree. They are in large colonies and there are larger all black bugs that appear to corral and guide the colony around. They do not appear to fly. I have at least 6 different swarms of these on one tree. Each group is a different age-- there is one colony of teeny tiny bugs that are about a millimeter or two in length and then there is another group that is a little bit larger, and so on. Any ideas?? Are they bad for the trees or good? Please help!