Beetles in the family Chrysomelidae are commonly called leaf beetles. It is of the largest beetle families and among the phytophagous (plant-eating) beetles. Chrysomelids are second in number of species only to the weevil, family Curculionidae. There are as many as 35,000 described species and perhaps up to 60,000 total species. Presently, the Chrysomelidae are classified in 195 genera and approximately 1,720 valid species and subspecies (plus 149 Bruchinae species) accepted as occurring in North America north of Mexico. [1]

Leaf beetles feed strictly on plant materials. The adults usually consume leaves, stems, flowers, and pollen. Most larvae are subterranean in habit, feeding on roots and rootlets, but others will consume foliage as well. Many chrysomelids are very specific to particular host plants, but most are able to live on a variety of plants; i.e. the so-called dogbane leaf beetle, Chrysochus auratus, which feeds on prairie plants such as milkweed (Asclepias sp.) and plants in the dogbane genus Apocynum. [2]

References

1. JR, Ross H. Arnett et al., American Beetles, Volume II: Polyphaga: Scarabaeoidea through Curculionoidea, 1st ed. (CRC, 2002).  
2. Jürgen Gross, On the Evolution of Host Plant Specialization in Leaf Beetles (Logos, 2001).