Size of leafy spurge (Euphorbia esula L) roots and their location in the soil profile are important factors relating to survival offirst-instar black dot flea beetle (Aphthona nigriscutis Foudras) larvae. First-instar larvae must find leafy spurge roots between 1 to 4 mm diam in the first 2 days after hatching from eggs for survival. In field studies, we ddermined that most flea beetle larvae reside within 7.6 em ofthe soil surface. Their location in the upper areas ofthe soil profile allows accessibility to desirable size roots, however the larvae are more susceptible to freezing temperatures in this region. Overall, there were fewer black dot flea beetle larvae in the soil at the Pollock site in 1997 compared to 1995 and 1996. In 1997, harsh winter weather conditions may have resulted in high mortality of larvae.
Clay, Sharon A.; Brinkman, Mark A.; Kramer, Robert J.; Jackson, Jan J.; and Granholm, Nels H., "Leafy Spurge Biological Control Using Black Dot Flea Beetles and Deleterious Rhizobacteria: Final Report Submitted to South Dakota Department of Agriculture Weed and Pest Control" (1998). Agronomy, Horticulture and Plant Science Faculty Publications. 218.