Novel hostplants require novel behaviors: canal-cutting in a euphorb-feeding caterpillar, Theroa zethus (Notodontidae)

Unlike most notodontid caterpillars, which occur almost exclusively on woody plants, Theroa zethus larvae feed on euphorbs that are not only herbaceous, but also protected by latex canals. The tree-feeding notodontids often girdle host stems and petioles, presumably to prevent inducible defensive responses. Theroa larvae show modified girdling on euphorbs with thick stems such as Euphorbia corollata. On the prostate euphorb Chamaesyce maculata, which has narrow stems, Theroa larvae in all instars crimp or sever stems, petioles, and midribs. They thereby reduce or eliminate the outflow of latex distal to the cuts where they feed.