Callirhytis carmelensis
Callirhytis carmelensis, formerly Andricus carmelensis, the mottled acorn gall wasp, is a species of hymenopteran that induces galls on the acorns of coast live oaks and interior live oaks in California in North America. The purple or spotted green gall forms where the acorn attaches to the tree and often prevents normal development of the nut. The gall also produces a honeydew secretion that is attractive to other insects. This wasp is generally considered uncommon.

References

External links 
 

Cynipidae
Gall-inducing insects
Insects of the United States
Oak galls
Western North American coastal fauna
Insects described in 1922
Hymenoptera of North America