Catkin-gall
Guides
Callirhytis congregata
sausage flower gall wasp
Callirhytis congregata is a cynipid gall wasp native to California that induces distinctive galls on the catkins of three oak species: coast live oak (Quercus agrifolia), interior live oak (Quercus wislizeni), and canyon live oak (Quercus chrysolepis). The species was originally described by William Harris Ashmead in 1896 under the genus Andricus. It is considered locally common within its range. The galls are described as rugose, yellowish-brown woody swellings with multiple cells, appearing to grow from the tips of slender twigs with a long peduncle-like base.
Callirhytis quercusoperator
Woolly Catkin Gall Wasp
Callirhytis quercusoperator is a cynipid gall wasp that induces galls on oak catkins. The species exhibits a complex life cycle with alternating generations, a common trait among Cynipidae. The galls produced by this species are characterized by a woolly or fuzzy appearance on catkins of oak trees. First described by Osten Sacken in 1862, it remains an active subject of observation with over 1,000 records on iNaturalist.
Eriophyes neoessigi
cottonwood catkin gall mite
Eriophyes neoessigi is an eriophyid mite species commonly known as the cottonwood catkin gall mite. It is documented on iNaturalist with 168 observations. The species belongs to the genus Eriophyes, which includes gall-forming mites that induce characteristic plant deformities. Unlike the related Eriophyes dimocarpi, which causes witches' broom disease in longan trees, E. neoessigi is associated with cottonwood (Populus spp.) and specifically targets catkins.