Sex on Six Legs_ Lessons on Life, Love, and Language From the Insect World - Marlene Zuk [96]
In groups, however, the caterpillars, like schoolchildren egging each other on to eat Doritos and Twinkies instead of carrot sticks, will often end up choosing the less nourishing offering. The problem seems to occur because, like ants, the caterpillars follow odor trails left by their companions. The initial decision to taste one or another of the foods is made at random, but once a caterpillar has started eating, its odor trail encourages others to follow, and then the entire gang gets trapped by heeding the message that went before it. The caterpillars thus follow each other to their collective nutritional doom. Unlike the bees or ants, the caterpillars lack any capability of communicating their state to each other, so they cannot indicate that they have arrived at a less tasty branch and warn others of their folly. Nietzsche's pessimism about groups seems to be better illustrated by the caterpillars than the bees in this regard, which makes you wonder whether we are so close to the social insects after all. Luckily, the caterpillars differ in their tendency to move around, and if a large proportion of the group was of a more active predilection, the group itself was less cohesive and managed to escape the poor decision.
Flying versus Walking, and the Lead-up to Language
DECISIONS about food or nest sites are closely tied to the success or failure of any given insect colony, and the way that different species get help when an individual finds a food item that is too big for it, or needs to get everyone else on board with a decision has important implications for social behavior. The way that an insect recruits is, in turn, constrained by its own biology. Ants, as I've discussed, lay down an odor trail that becomes stronger and stronger as more workers use it, but to each ant that traverses the trail, its end point is a mystery—she simply follows her nose, so to speak, until she reaches the goal. In the case of establishing a new nest, ants can be carried by their nest mates to the new site, and again those being unceremoniously tucked under a leg need have no idea of where they are being taken.
Bees are different. Flying instead of walking means that you can't easily haul your sister workers around, which means that the bees need some other way to convey information to the rest of the colony. And although some species of bees do place dabs of odor on plants and other objects as signposts on the way to a food source, pheromones are not nearly as satisfactory a method for indicating directions for flying insects as they are for crawling ones; the bees have to continually dart down to the vegetation, and the odors fade without continual reinforcement by a stream of workers.
What's more, at least some kinds of bees have to worry about eavesdroppers on their odor cues. James Nieh at the University of California at San Diego has been studying tropical stingless bees in Brazil, Panama, and other parts of Latin America for many years. The stingless bees are social, like honeybees, and Nieh noticed that the species he was studying left scent marks near good food sources. The problem was that the scent marks were easily detected by a larger and more aggressive species of stingless bee, and when the bullies found the food, they dispatched their victims with what Nieh describes as "a range of forms of aggression from threats to intense grappling followed by decapitation." The victim species avoids the odor marks left by the aggressor species and sticks to its own signals, but the aggressor does the opposite,