Adkins Arboretum Mystery Monday: Guess the Photo!

The answer to last week’s mystery is cypress twig gall midge, Taxodiomyia cupressiananassa, pictured in photo #2.

Nope, they’re not pinecones! The spongy, powdery balls encasing the cypress twigs pictured are caused by the larvae of a tiny fly, the cypress twig gall midge. Female twig gall midges lay a cluster of eggs on young cypress leaves. The growing maggots induce the midrib of the leaf to swell into a gall. A single gall can contain a dozen or more larvae.

The galls are most noticeable in late Spring and Summer, appearing as white or greenish-white.

Insecticide is not recommended because the galls do not harm the tree and there is no good, practical treatment for controlling them. Gall midge outbreaks are somewhat sporadic and a tree that was heavily infested with galls one year may have only a few galls in subsequent years.

Mystery Monday is sponsored by the Spy Newspapers and Adkins Arboretum.