Response of a fifth-instar Cactoblastis cactorum caterpillar to an artificial trail prepared from mandibular gland extract. The pencil dots show the location of the trail. From the paper titled “Trail marking by larvae of the cactus moth, Cactoblastis cactorum” by Fitzergald et al., published in the Journal of Insect Science. Available online here: www.insectscience.org/14.64