Quadrastichus erythrinae, erythrina gall wasp, on flowers of wiliwili (Erythrina sandwicensis). Keaau Valley, Makua-Keaau FR. This area formerly had a dense grove of trees, but many were killed by the wasp. Even though it is largely controlled now, many of the surviving trees are mostly dead, and the wasp continues to cause damage to flowers and seed pods.