200 NEW YORK STATE MUSEUM 



Life history. Messrs Russell and Hooker state that the midges 

 emerge from the ground from May ist to the 20th, all disappearing 

 by June ist. May 4, 1908 five adults were captured and by the 

 nth the insects occurred in thousands, being so numerous that it 

 was only necessary to sweep an open cyanid jar over the top of, and 

 through the grass to obtain all the specimens desired. The flies appear 

 just as the leaves begin to unfold and, for a time, after emerging, 

 large numbers may be found in the early morning and on wet days, 

 especially under the tree. As it becomes warmer and the dew driss 

 they rise among the branches. The flight is feeble and the insects 

 do not fly out beyond the borders of the tree. Oviposition begins 

 when the leaves are i to 2 inches long, the eggs being deposited for 

 the most part upon the under side and irregularly scattered between 

 the veins. A few are laid, apparently by accident, upon the upper 

 surface. An average of 70 eggs was obtained from each of 50 leaves, 

 not over 6 being upon the upper surface, the total number varying 

 from 40 to 120. One leaf if inches wide bore 281 eggs on its lower 

 surface and 175 on the upper. The eggs hatch in from 4 to 6 days, 

 the time varying with the weather. The young larvae migrate at 

 once to the edge of the leaf or to any hole in it and begin to feed on 

 the upper surface. After about 4 days of this feeding the edge 

 begins to curl over on the upper surface, forming a roll, the upper 

 face of which becomes more or less reddish. The larvae feed within 

 this roll, extending it with the growth of the leaf. Occasionally a 

 young larva feeds for a time in a circle on the exposed surface of 

 the leaf, causing it to become reddish and wrinkled. May 2 2d 

 nearly all the leaves near the ground bore rolls which, in some cases, 

 nearly encircled the leaf, while in others they were about one-fourth 

 of an inch long. One roll an inch long contained 25 larvae, while 

 only a few were present in others. The longer rolls are said to con- 

 tain relatively fewer larvae. The larval stage persists through the 

 summer, full growth being attained by the last of September or the 

 first of October, at which time all except those parasitized enter 

 the ground and pupate prior to cold weather. Exceptionally full- 

 grown larvae may be unable to escape and winter in the roll, the 

 adults appearing at the usual time in the spring. 



Natural enemies. This species is attacked by a chalcid egg para- 

 site which appears at the same time in swarms almost as large as 

 those of the host. The female chalcid walks around among the 

 midge eggs, touching them rapidly with her antennae and stopping 

 every now and then to insert her ovipositor and lay an egg in that 

 of the host, neglecting others in the immediate vicinity. A mite 



