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Digitizing and providing web access to this text was funded in part by the Alberta Conservation Association and the University of Alberta, Department of Biological Sciences

Lepidoptera(Aquatic Caterpillars)

The order Lepidoptera contains the moths and butterflies, the larvae of many being called caterpillars. This is a very large order of insects-over 100,000 species world-wide and over 10,000 in North America. Most species are entirely terrestrial. There have been no studies of "aquatic" lepidopterans of Alberta.

Few lepidopterans are truly aquatic, in the sense that the larvae are submerged throughout most if not all of the larval stage. Many so-called aquatic lepidopterans are semi-aquatic at best. The larvae of some aquatic lepidopterans are closely associated with aquatic plants, especially water lilies, living on the underside of the leaf or mining into the plant (Fig 39.A and Plate 39.1). Aquatic larvae, as true of terrestrial caterpillars, feed mainly on a variety of plant material, such as cattails, water lilies and bulrushes (Lange 1984). Many aquatic lepidopteran larvae construct cases out of a variety of plant material. Most lepidopterans have three or more larval molts. Pupation takes place in the water, usually in a silken-cocoon, which is often attached to aquatic plants. Adults usually do not enter the water to deposit eggs (Lange 1956).

The LEPIDOPTERA pictorial key only includes lepidopterans that are usually considered truly aquatic, and only some of the taxa possibly occurring in Alberta. The key should be used with caution. The pictorial key should serve to separate lepidopteran larvae (be they aquatic, semi-aquatic or terrestrial) from similar appearing larvae. In this respect, note the four pairs of prolegs on the abdomen of caterpillars. For a detailed taxonomic treatment of aquatic lepidopterans, see Lange (1984).

Pictorial Keys



  • Plate 39.1
    Upper, left to right: Sialis sp. (Megaloptera: Sialidae) [15 mm], Sisyra fuscata (Neuroptera: Sisryidae) [4 mm],.
    Middle, left to right: Paraponyx sp. (Lepidoptera) [40 mm], unidentified leaf mining lepidopteran [50 mm].
    Lower: Isotomus (Collembola) [2 mm].