5.—The form of the gall is an indicator of the specific nature of the insect and also of the generic relations of the insect; the degree of complexity of the gall-structure is likewise an expression of the generic position of the insect, the simplest galls being produced by the most primitive gall-wasps, and the more complex galls by more specialized wasps. The primitive cynipids were plant-tissue inhabiting, not gall-making, insects.
Figure 1. Relations of some cynipid genera.
6.—The primitive Cynipidae were bisexual species with normal, sexual reproduction. By the gradual disappearance of the male and the gradual increase of parthenogenetic reproduction, species have become agamic at several times along distinct lines of evolution within the history of the gall-wasps.
