The cypress twig gall midge, Taxodiomyia cupressiananassa (Osten Sacken), attacks bald cypress (Taxodium distichum) and pond cypress (T. ascendens), inducing galls that develop from leaf bud tissue ...
DISTRIBUTION
This midge is found in the midsection of the U.S. from north Illinois, Indiana to Florida and west to Louisiana, Tennessee, and Alabama.
DESCRIPTION
ADULTS
The adults are tiny flies with hyaline wings covered with short setae. The thorax and appendages of males are tan and the abdomen is tan-orange. The abdomen of the female is orange-red. Males and females are approximately 1.57 and 2.17 mm long, respectively.
EGGS
The eggs are bright orange, translucent, about 0.6 mm long by 0.08 mm wide, and average 15 eggs per cluster.
LARVAE
The larvae when newly hatched are light orange, about 0.6 mm long by 0.09 mm wide. At this point the sternal spatula is not visible but becomes visible as larvae mature, it then changes color to orange-red and reaches about 1.5 mm long by 0.072 mm wide.
PUPAE
The pupae are obtect (wings and appendages are appressed to the body ) and bright orange. Males and females are approximately 1.53 mm and 1.84 mm long, respectively.
The oval shaped galls are formed on the terminal portion of the branchlets. When mature they resemble miniature pineapples that look like elongate swellings on the leaflets. The color varies from pink at first, turning light green as development progresses. However, the galls appear white most of the time because of a covering of fine, powdery material. When adults emerge the galls turn brown. Overwintering galls are usually copper-brown, dropping with branchlets in late autumn. The galls average 20 mm in length, but larger galls may reach 3 cm in length and 2 cm in width and may contain an average of 16 larvae. The number of midge larvae inside is highly correlated with the length of the gall. The gall tissue is spongy and succulent but becomes less succulent as the midge larvae mature.
LIFE CYCLE AND BIOLOGY
The life cycle of T. cupressiananassa is univoltine in the northern U.S. and bivoltine (two generations) in northern Florida.
The flies overwinter as larvae on the ground in the fallen galls in early November and pupate in mid-April inside the galls.
Adults flies emerge in mid-May for an extended period of time. Nearly 95% of the adult midges emerge within three weeks of the onset of emergence. Copulation occurs the same day as adult emergence. After mating, the female midge flies to the leaves where it oviposits on the new developing foliage an average of 120 eggs during their one to two day life span.
The midge larvae induce gall formation by the leaflets initiating as pink swellings of the branchlets at the feeding sites. Galls rapidly increase in size during the first three weeks and at the same time, larvae gradually move toward the longitudinal axis of the gall where each larva makes a small chamber which it occupies. Before pupation, the larvae reverse their position so that their heads point toward the gall surface.
For adult emergence, the pupa moves through the larval chamber and breaks the gall surface until its head and thorax are completely outside. The second generation feeds until mid-September and in late October the galls and foliage fall from the trees....
