Overview:  Long-horned leaf beetles inhabit the sphagnum bogs that are near low elevation (below 1000m) lakes.  Adult beetles feed on the exposed leaves and shoots of aquatic plants, such as lilies and potomagon.  Leaf beetle larvae feed on the submerged portions of those plants.  A unique feature of the Donacia beetle larva is its posterior sharp-pointed breathing tube, which it thrusts into the vascular tissues of the water plant it is feeding upon in order to siphon the plant's supply of oxygen.  This adaptation allows the larvae to breathe while submerged.  The draining and filling of peat bogs for agriculture and development continue to be the predominant threat to the survival of these beetles.  Harvesting of the peat mats, which take hundreds of years to build up, is also harmful for all the organisms that make their homes in sensitive sphagnum bog habitat.  Another threat to these beetles is the run-off of stormwater containing pesticides, as well as the deliberate diversion of stormwater, into the bogs from surrounding developed areas.

Distribution: The distribution of the long-horned leaf beetle includes Washington and parts of southwest British Columbia.  In Washington, the only known populations of these beetles occur in Snohomish County.