National Geographic : 1974 Jul
" T"OW do ants 'talk'?" I asked biologist Caryl P. Haskins, a former President of the Carnegie Insti tution of Washington, who has studied the bulldog for 25 years. "How do workers know when to assist a larva in cocoon build ing or when to help the adult ant out of its silken shell?" "Basically they signal with odors," Dr. Haskins told me. "Adults, of course, also com municate by sight and touch, but scents-scientists call them pheromones-seem to be the chief trigger of ant behavior. Probably the young larva pro duces one of these chemical messages when it is ready to spin its cocoon." A bulldog larva needs a framework to help build its new home, so older sisters cover the creature with twigs and sand (left, upper). The larva attaches strands of silken thread, extruded from glands below its mouth, to the grains of sand. Weaving its head back and forth, it completes its home beneath the growing pile of debris (center). After a few days workers unearth the freshly spun light yellow cocoon (bottom), which will soon darken to match the older cocoons in the back of the chamber. During the next two months the larva will slow ly change into an adult ant.