IOO MAINE AGRICULTURAL EXPERIMENT STATION. I9O2. 



genetic eggs. The males are not as slender as the females, and 

 they differ from them somewhat in the position and shape of 

 parts. The eves are placed more dorsally. The prothorax is large, 

 and has a pair of large spines at its posterior angle on each side. 

 The mesothorax is short, and as seen from the dorsal surface, 

 is nearly round in outline. The small metathorax has its line of 

 junction with the mesothorax semicircular, and its posterior out- 

 line straight. The abdomen is quite narrow in front and grows 

 gradually wider posteriorly as far as the fourth somite. From 

 this point it tapers gradually to the posterior end of the body. 

 The last somite is modified to form the male copulatory appa- 

 ratus. This somite bears two pairs of large, long spines. 



LIFE HISTORY. 



The adult insects pass the winter months in the dead vegeta- 

 tion at the bases of their host plants, very close to or on the 

 ground, where they are protected by the debris. In the spring 

 as soon as the weather has become sufficiently warm to start the 

 grass, they come out from their winter quarters and begin to lay 

 eggs in the tender leaves of the young grass. The eggs are 

 deposited in the tissues of the blades near their upper surfaces. 

 Fernald and Hind * determined by keeping insects in captivity 

 that each female is capable of laying from fifty to sixty eggs. 

 The first eggs laid hatch in from twelve to fifteen days. Later 

 in the season the time required is materially reduced. In the hot 

 dry periods of the summer they may hatch in a week. 



When the larvse are hatched they seek some sheltered place in 

 which to pass the next stages of their development. At this 

 period of their development they are most frequently found in 

 the sheaths of the blades, especially those of the young stalks, 

 near the ground. In the later stages the}' sometimes congregate 

 in the upper sheaths of the stem, and then they cause the "silver 

 top,"' which is the most conspicuous evidence of their work. 



The larvae, especially in the later stages, are quite active, run- 

 ning about the leaves inside of the sheath or even on the head, 

 among the flowers. The pupal stage is passed in some quiet 

 place, as at the base of the sheath of some lower leaf. In this 

 stage the insect takes no food and moves only very sluggishly. 



* The Grass Thrips. Bnl. 67, May, 1900. Hatch Exp. Sta., Mass. A gT. College. 



