Fig. 1.

Diagram of the head of a caterpillar, as viewed from below. An enlargement of one maxilla (indicated with anarrow) is provided to show the locations of the medial and lateral styloconic sensilla. The epipharyngeal sensilla are located underneath the labrum and thus are not visible in this diagram. Each of these gustatory sensilla contains one bitter-sensitive taste cell. We indicate which bitter-sensitive taste cells exhibit a vigorous excitatory response to caffeine and aristolochic acid in theright panel; these latter data are fromGlendinning et al. (1999a). This illustration was adapted from Bernays and Chapman (1994, their Fig. 3.4).