Figure 2. Flea beetle larval morphology. More photos and information may be found in the species' descriptions in Appendix 3.
Leaf-feeding Red Ptocadica larva, similar in appearance to ant tended larvae of Lycaenidae and Riodenidae. Note how the legs and head are covered by the enlarged dorsal surface. Pt. bifasciata larvae look the same. Ptocadica larvae do not posess the "balloon organs" found in Parchicola, Monomacra and Disonycha. Stem/root feeding Parchicola "yellow tibia" larva. Tiny spherical "balloon organs" are found on the ends of the dorsal protuberances. Similar organs are found on larvae of Parchicola DF2, Monomacra violacea and Disonycha quinquelineata.
3rd instar Red Pedilia larva, feeding on stem epidermis. The first stage larvae feed on the leaves where the eggs are laid. Monomacra violacea larvae feed on rootlets near the base of the P. lobata host plant. M. violacea larvae have two rows of "balloon organ" setae per segment, unlike Parchicola species with only one row.
Disonycha quinquelineata larvae are leaf eaters, but have the tiny balloon organs of the root/stem feeders. Side view of the balloon organs of D. quinquelineata. Parchicola and Monomacra organs are much shorter and more spherical.