Family Haliplidae (Coleoptera Order) are water beetles commonly found in North America and Europe. These insects are among the most common of the aquatic Coleoptera. Areas of slow moving or still water are the favored habitats. All Haliplidae have elytron (wing covers) on their backs. Elytra puctations, small holes in the elytra, create the illusion of lines along the back of the beetles. Haliplidae gain oxygen from the surface air and are able to stay under water because they maintain air bubbles that can supply enough oxygen. Surprisingly, these water beetles are terrible swimmers!! They are not helped by the very air bubble that allows them to remain under water for long periods of time. However, the beetles walk very well, so they usually walk on the vegetation instead of swimming (Hickman, 1931).
Genus Peltodytes are the smaller of the two genera studied. These little guys have small rounded bodies. The spots on the back tend to also be rounded and are not connected to each other. On the coller of the Peltodytes, two small dots can be identified that clearly mark Peltodytes from other species.
P. edentulus has a clearly visible black band on its head.
P. lengi are identified by their banded hind femurs.
P. muticus has their two sutural blotches connect together.
P. sexmaculatus have no outstanding identifying features, except for the separation of the sutural blotches.
P. shermani have large subhumeral blotches. Occasionally, P. sexmaculatus has very small subhumeral blotches, but P. shermani's are always large and triangular.
Genus Haliplus are longer and larger than Peltodytes. The spots on the back of Haliplus are larger and more connected.
H. triopsis have a black band on the collar, not to be confused with the two small black dots that identify Peltodytes.
H. fasciatus are very large, easily the largest of the Haliplidae.
Mandibles are hard, short appendages on the head of insects used for sucking or chewing food for ingestion. Mandibles have two basic regions: the incisor region and the molar region. In phytophagous insects, the mandibles are short. The incisor region is designed to cut the plant and the molar region to chew the plant to smaller pieces. Predaceous insects have long, pointed manibles. The molar has very strong cusps or a ridge used to tear the prey apart (Chapman, 1995).
Maxella appear to be important to the food handling of the Haliplidae. Maxella are long and pointed with long hairs or spines along the inside ridge.
Questions we wanted to answer were as follows: