For Some Insects, It's Smart to Run With the Crowd | Science Blog:
The researchers discovered that for the crickets, there's safety in large numbers. Those insects which were part of a large moving band were much less likely to be eaten. In fact, 50 to 60 percent of the Mormon crickets that were separated from a migratory band were killed within two days by predators such as birds and rodents, while none of those staying with the band were eaten. Radio transmitters belonging to those unfortunate, lone insects were found either chewed or still glued to a partially-eaten cricket corpse.
Natural selection at work. Just another day in the exciting world of evolutionary biology. Testable evolutionary hypotheses, and positive results.