History, Distribution, Damage, and Life Cycle of a Pine Shoot Gall Sawfly, Xyela gallicaulis (Hymenoptera: Xyelidae)

Larvae of Xyela gallicaulis Smith cause shoot stem galls in young pines. Loblolly pine, Pinus taeda L., is the most seriously damaged, but galls have been observed on slash pine, P. elliottii var. elliottii Engelm., and shortleaf pine, P. echinata Mill. Studies in Virginia and Georgia confirm a 2-year life cycle. Larval development takes 4 - 6 wks. After feeding, larvae bore out of the galls and drop to the ground where they form a papery cocoon in the soil to pupate, and where they remain for 22 - 25 months. Adults emerge from cells constructed in the soil from early-December to mid-January of the second year. Eggs are inserted into the vegetative buds during odd-numbered years. Insect associates found feeding in or on gall tissues are the Nantucket pine tip moth, Rhyacionia frustrana (Comstock) (Tortricidae), and the weevil Conotrachelus carolinensis Schoof (Curculionidae).