Atriplex leaf beetle study
John Smiley
Location: Poleta flats near Owens River, Inyo County, CA

Host plant: Atriplex lentiformis ssp. Torreyi (Big Saltbush)
Herbivore: Altriplex leaf beetle Monoxia sp.? (Coleoptera: Chrysomelidae: Galerucinae;

Field Notes (John Smiley): About May 30 I noticed large aggregations of tiny pale colored beetles feeding on the upper branches of saltbush, growing on the flats between the WMRS Owens Valley Lab and the Owens River. I noticed them again on several occasions, including on 6-22-4. On 6-27-04 Nathan Rank and I walked out to look for the aggregations. The beetles had mostly abandoned their large aggregation to the northeast of the Collins Ditch canal, so we walked to the west along the road paralleling the ditch. After about 200’ we encountered a large aggregation on saltbush growing on both sides of the road. Further observation along the road to the east from the aggregation showed that many of the saltbush plants had been previously defoliated by the leaf beetle, but not along the road to the west, as if the beetle population had been moving westward from where I had seen the beetles earlier.

The beetles are very apt to take flight in swarms, make tightly curving flight trajectories, and land. I could not find any larvae or eggs on the Atriplex foliage; however, Monoxia sp. are known to be leaf miners and I did not specifically examine the leaves for mines. It may be that the adult beetles aggregate after eclosing from their mines, which may be more dispersed than the adult aggregations.

Other researchers conducting vegetation transects in the Owens Valley (for the Inyo County Water Department) have recorded large numbers of these beetles feeding on saltbush. They refer to them in their field notes as "atto beetles," so named for their host plant Atriplex lentiformis ssp. Torreyi. They are recorded as being exceedingly common in some areas.

Other notes: Monoxia pererbula are known to feed on Broom Snakeweed (Gutierrezia sp. ; Asteraceae) in New Mexico (see web page and photos), and Monoxia batisia is known to feed on on Pickleweed (Batis maritima; Bataceae) and Box Thorn (Lycium sp.; Solanaceae). For copyrighted photos of other species of Monoxia, see adult and leaf-miner larva .

Note: click on photo to see full sized version...

Closeup of flea beetles feeding on saltbush (6-28-04)	From a distance the beetles look like dark clumps at the bases of the twigs. (6-28-04)
Here is a photo of an uninfested saltbush (6-24-04). Something defoliated the upper branches in the past.