Disholcaspis eldoradensis
Agamic generation

[Photos of this gall appear on page 4 of the pdf]

GALL (Fig. 6). On last year's twigs in the intervals between buds, sometimes close together; usually on fast-growing relatively young trees. Galls are oriented along the twig, but seldom evenly or in rows. Number may vary from one to several dozen; relatively small numbers on robust twigs attain greater size and more perfect shape than those in large colonies on small twigs, which may be distorted by crowding; monothalamous. Circular emergence holes are usually at the ends of the galls. The hard broken shells and deep scars may remain on a tree for years; small twigs are often killed by the galls. Frequently the same tree is utilized for the agamic generation year after year, and develops a clipped stunted appearance.

Range: San Francisco area

Adults of the bisexual generation emerge during April and May, and oviposit in the twig bark. Gall colonies usually result from one female rather than from communal oviposition. First evidence of a gall is a slight swelling of the bark, which splits longitudinally as the gall develops. Very young galls are yellow, changing to green, brown, and shiny dark red by early autumn; thereafter the color becomes dull and darker. Agamic females emerge during November and December and oviposit in buds at that time.

- David Evans: (1972) Alternate generations of gall cynipids (Hymenoptera: Cynipidae) on Garry oak^©