The gall's range is computed from the range of all hosts that the gall occurs on. In some cases we have evidence that the gall does not occur across the full range of the hosts and we will remove these places from the range. For undescribed species we will show the expected range based on hosts plus where the galls have been observed.
Arizona, Sycamore Flat, Nov. 21, 1918, collected by G. Hofer, specimens 1(3), USNM.
Arizona, Wolf Creek, Sep. 26, 1945, collected by L. H. Weld, specimens 1(2), USNM.
Quercus sp.:
Arizona, east of Vail, Jun. 1918, collected by GFF, specimen 1(1), UCO.
Gall Description:
The galls, located on the undersurface of the leaf, are 10–12 mm long, 6–8 mm wide at the base, compressed laterally to 5–9 mm, and taper into a sharp point. The gall opening is an elongate slit parallel to the midrib on the upper surface of the leaf. Two to four galls may be on a single leaf; occasionally, two galls are fused. Dry galls are hard and woody. The female fills the lower or pointed end of the cavity of the gall and lies with its dorsum toward the opening. The overall shape of the female is conical, conforming to the shape of the cavity, with a heavily sclerotized, flat, circular dorsum and a membranous or slightly sclerotized venter.
It remains questionable how the first instars escape from under the female and through the opening of the gall. Nymphs that were found inside the gall, on the leaves, or near bud regions were used for this study. No information is available on the overwintering stage, on the instar starting the gall, or on the males. O. cristicola habitat in Arizona is given in Color Figure 4.
