3l6 CONNECTICUT EXPERIMENT STATION REPORT, I907-I908. 



night, and are strongly attracted by electric lights. The adults, 

 cocoons, winter nests and egg-masses are shown on Plate XIV. 

 See also Figures i, 2 and 3. 



Food Plants. 



Femald and Kirkland give a list* of about eighty species of 

 trees and plants on which the caterpillars are known to feed. 

 The pear is the first preference of the caterpillars, followed 

 by the apple and the stone fruits. Maples, elms and oaks 

 are perhaps the chief kinds of shade and forest trees liable to 

 be injured. As the gypsy caterpillars feed upon over six 

 hundred different kinds of plants, it will be seen that the brown- 

 tail is much more limited in regard to its food plants. Pear, 

 apple and oak trees are stripped by the brown-tail caterpillars. 



Irritj^tion Caused by the Caterpillars. 



The hairs of the caterpillars are barbed and brittle, and break 

 off easily. When they come in contact with the human skin, 

 they cause an irritation or rash which is quite serious with 

 certain persons. The worst forms of rash are caused by actual 

 contact with the caterpillars, but the broken hairs which blow 

 about will cause the milder forms. The matter has been care- 

 fully studied by Dn E. E. Tyzzerf of the Harvard Medical 

 School, who finds in these hairs a definite poisonous principle 

 which causes certain changes in the blood. The long hairs do 

 not seem to possess this quality, but the short barbed hairs of 

 the red dorsal tubercles are the ones chiefly responsible, though 

 similar hairs occur with the long ones on various portions of 

 the caterpillar, and on the posterior extremity of the body of 

 the adult. In making the cocoon the hairs are rubbed from the 

 caterpillar and woven into the new structure, and those from 

 the adult female are worked into the formation of the egg-mass, 

 so that either cocoon or egg-mass may produce the rash. Such 

 hairs are doubtless cast with the skin when the caterpillars molt, 

 and are often rubbed or broken off from their bodies and blown 



*The Brown-Tail Moth, Mass. Board of Agriculture, p. 57. 1903. 

 t Second Annual Report of the Superintendent for Suppressing the 

 Gypsy and Brown-Tail Moths, p. 154. 1907. 



