Whitish egg cases from which hatched larvae of elm leaf beetle, Xanthogaleruca luteola (lower left and right), and egg cases that are golden colored because they contained egg parasites, Oomyzus (=Tetrastichus) gallerucae.

Eggs from which elm leaf beetle larvae emerged (white) and Tetrastichus gallerucae emerged (golden) on leaf, UC Berkeley Insectary Credit: Jack Kelly Clark
Credit: Jack Kelly Clark