2 



hopper will indicate its presence by flying away with a distinct 

 buzzing noise from the trees approached, and, as it is a very shy 

 insect, there is some difficulty in coming close enough to see it at 

 work and observe its methods. (Jnce well engaged in oviposition, 

 however, it becomes for the time being fearless, and may be closely 

 watched, even under a hand lens. 



Where alnmdant the smaller limbs of trees are often completely 

 scarified over cheir upper and lateral surfaces, so that the trees 

 become dwarfed or bark-bound, make a sickly growth, and are ren- 

 dered more liable to the attacks of wood-boring insects. This latter 

 source of injury was first prominently brought to our notice in a 

 communication from Mr. J. A. Pettigrew, superintendent of Lincoln 

 Park, Chicago, who described the attacks of a borer in the smaller 

 branches of the cottonwood, Popidus inonilifera, which caused 

 the limbs to break off and fall to the ground in great numbers. 

 Examination of the twigs submitted by him showed at once that 

 the}" had been oviposited in very abundantly by the buffalo tree- 

 hopper a year or two before, and that the old scars from the egg- 

 punctures of this insect had furnished favorable conditions for the 

 attacks of a wood-boring beetle, Oberea schaumii Lee. This beetle 

 had deposited its eggs in the diseased spots left by the Ceresa, and 

 the larvae of the beetle had burrowed up and down the twigs, weak- 

 ening them and causing them to ln*eak off and fall as described. 

 Healthy twigs would be distasteful or unsatisfactory to this insect, 

 but the diseased condition, and particularly the dead spots left by 

 the Ceresa, furnish the very conditions most favorable for this wood- 

 borer, as similar injuries do for many other wood-boring insects. 



HABITS AND LIFE HISTORY. 



The habits and life-history of the buffalo tree-hoi^per are as follows : 

 The adult insect chooses as a nidus for its eggs the twigs, preferably 

 those of two or three years' growth, of various trees, particularly the 

 apple, Avillow, cottonwood, maple, etc., confines itself in general to 

 the upper surface of the twigs, and works more abundantly on the 

 south side of the tree than on the north, although in this respect the 

 prevailing winds and other conditions influence the insect. The eggs 

 are deposited quite as readily in the new growth of old trees as in 

 j'oung trees, but the damage is much more noticeable in the latter 

 case. The eggs are placed in small compound groups of from G to 

 13 eggs each, arranged in two nearly parallel or slightly curved slits 

 extending in the direction of the twig about three-sixteenths of an 

 inch in length, and separated by one-eighth inch or less of bark 

 (fig. 2, 6). 



In depositing the eggs the bark is cut by the ovipositor in such a 

 way that the narrow bark intervening between the two incisions is 



