Identification and Control . Gall Production Gall: An abnormal plant growth caused by the action of insects or other organisms. Gall Production ... Oak Apple Galls. Most species of gall wasps live as gall-formers on oaks. Oak apple or oak gall is the common name for a large, round, vaguely apple-like gall commonly found on many species of oak.Oak apples range in size from 2 to 4 centimetres (1 to 2 in) in diameter and are caused by chemicals injected by the larva of certain kinds of gall wasp in the family Cynipidae. Galls affecting leaves are seldom if ever a serious problem. It's just a first draft, so comments and suggestions are very welcome! Infection of oak causes small brown or yellowing areas on the leaves. These growths typically emerge at bud break in the early spring. Found on the twigs of spruce trees, often Norway spruce. The adult female wasp lays single eggs in developing leaf buds. Jumping Oak Gall. Inside the gall, there are a number of chambers, each housing a larva which eats its way out. The oak apple gall wasp, Biorhiza pallida, is a tiny wasp that causes growths, or 'galls', on oak twigs. Gall Insect Management Trees species: Black Oak (Quercus kelloggii) Found in hilly regions between 2,000 and 6,000 feet. Typically associated with conifers and pines, firs, or incense cedars. They may also develop as a response to infections by several kinds of fungi, bacteria, and viruses. Iron-gall Ink A permanent ink derived from oak galls. Pine-Oak Gall Rust (Eastern Gall Rust): The fungus Cronartium quercuum causes gall rust on approximately 25 to 30 species of pine and oak. In an effort to simplify the identification of woolly looking oak galls in Texas, I pulled this info from BugGuide. Some galls form where insects or mites feed or lay eggs. Galls are abnormal growths caused when another organism interferes with a plant’s cells. Identify oak galls on your trees. Caused by a small wasp, they typically appear on the leaves of valley oak and California white oak. The data for the Texas observations on BugGuide is VERY limited. Adults emerge in June and July. Oak bullet gall are often found on bur and swamp white oaks where they can cause girdling and twig loss as well as attract numerous stinging insects. Several small larvae may be found inside the swollen folds of the leaf. On the underside of the leaves, yellow to orange powder (spores) is visible. The majority of species occur on oak trees (Quercus sp.). There are a number of common oak species in California including both tree species and shrub species. One of the most well-known is the common oak gall wasp (Cynips quercusfolii), which induces characteristic, 2-cm in diameter, spherical galls on the undersides of oak leaves. Texas Woolly Oak Galls. Inside of each gall is an individual larva feeding. The galls start small and green, become larger and red by midsummer, and finally brown knuckle-sized "bullets" by summer's end. California Oak Galls Wasps in the family Cynipidae are gall inducers on plants, or inquilines of gall inducers (living inside the galls made by other cynipids). Charley Eiseman advises that galls on Texas oaks are largely understudied. We have illustrated 12 of the most curious and colourful galls to look for. It was self-published in 1960 and has black-and-white photos. Caused by the aphid Adelges abietis. Diplolepis rosae, rose bedeguar gall. A related midge species causes the marginal folds or leaf pockets that can be found on red oak or pin oak. According to Bugguide, the on-line pamphlet, "Cynipid galls of the Southwest" by Lewis Hart Weld is the best source of info about SW galls, especially desert galls. Galls affecting twigs, such as the gouty oak gall and horned oak gall, can be more serious. These galls can be found between May and June where the female has laid her eggs in the leaf bud. Galls range in size from 1 mm to 6 cm or more and come in many shapes and colors, as depicted on this page. Symptoms and Diagnosis