“Some just wanted to roam away and eat,” said Elizabeth Brown, a biologist at Dr. Keenes laboratory. But if an insect spotted a bite of food being monopolized by another, it would “stand up and with its head make a leap onto the body of the other larva,” she said.
Sometimes the strikes landed near the receiver’s head. In other cases, it was a bit more like “a blow to the gut,” said Dr. Brown. Either way, the battered caterpillar would usually give way in defeat and free the milk porridge for the greedy victor.
That is a “big consequence”
The older and larger the larvae became, the more their contempt for sharing grew, the researchers found. The largest number of quarrels occurred among bugs in the last phase before metamorphosis, as the incidence of milkweed was probably particularly high.
Along with the docile reputation of most butterflies, the results of the study may be a little disorienting. “We think of monarchs as these beautiful, dazzling creatures flying around pollinating flowers and laying eggs,” said Adriana Briscoe, a butterfly researcher at the University of California, Irvine, who was not involved in the study. “We don’t usually think of them as this kind of darker abdomen.”
But even adult monarchs, especially men, can get a little picky when their territories are threatened, Dr. Green. In their cramped quarters, their younger, flying counterparts may have all the more reason to engage in occasional snails.
Dr. Green and Dr. Briscoe both pointed out that the results of the study were limited to the laboratory, leaving the possibility that the larval bath that the researchers witnessed could vary in nature, where there is more room to roam.