Besbicus mirabilis Kinsey Bisexual generation

GALL. About 3 mm. long; deeply embedded among the leaf buds. Superficially appearing smooth and subovoid, actually with fine longitudinal striation and a slight off-center protuberant apex; pale brown. Thin-walled with internal structure. The empty gall may persist on the twig until the following spring. Galls are usually single, but occasionally up to four or six may be found together.

Life History BISEXUAL GENERATION. The eggs for the bisexual generation are laid during warm (above 40" F.), calm dry days from late December to early February. They are subellipsoidal, approximately 0.10 mm. long by 0.06 mm. wide, and creamy white. The egg is inserted through the basal scales of the oak bud. The egg hatches within 10 days, and the larva remains inactive within the chamber of its incipient gall. Development to the second instar requires 4-6 weeks, but after that the growth is faster. By the end of March the gall is well formed, although not mature. The pupal stage lasts about 3 weeks, and pupae may be found from early April until mid-May. The emerging adult chews a large even exit hole through the outer end of the gall, usually decapping it (Fig. 6). The adult population contains about equal numbers of males and females. The adults are fragile, but competent fliers. Mating may occur any time after emergence; the females begin oviposition 1 or 2 days later, and egg laying may be continued over a period of several days. There is little apparent preference for host tree types by either the agamic or heterosexual females; only those trees of exceptionally vigorous growth seem less attractive to them. It is possible that such trees are actually utilized as much as others, but they are able to inhibit the development of the galls.

The heterosexual females oviposit during late April to mid-June.