Gall Formation, Outsiders and Soldiers of the Aphid Ceratovacuna japonica (Homoptera)

Gall formation of Ceratovacuna japonica was studied on the snowbell trees in Nagoya. It was found that the fundatrix transforms an axillary bud into its banana-bundle-shaped gall. A few outsiders appeared in the course of the gall formation. Many 2nd-instar sterile soldiers were produced in the gall. Outsiders known from other cerataphidines are reviewed and discussed. It is concluded that the evolution of 2nd-instar soldiers preceded that of outsiders in the history of the tribe Cerataphidini.