592 NEW YORK STATE MUSEUM 



color, without markings, and cylindric, except as its shape is modified by 

 pressure of the wood and adjacent eggs. The young resemble the adults 

 but are wingless and armed along the dorsal line with numerous forked or 

 barbed projections. The adult is a green insect, about 3 x inch in length, 

 and may be easily recognized by the greatly enlarged thorax which bears 

 on its anterior angles lateral projecting horns, as represented in figure 148. 



Life history. The life history of this insect has been given by Mr 

 Marlatt substantially as follows : 



The adult insect deposits her eggs in twigs 

 of various trees, preferably those of two or three 

 \ cars' growth, particularly the apple, willow, cot- 

 'tonwood, maple etc. and confines its operations 

 in general to the upper surface of the twigs. It 

 works more abundantly on the south side of 

 the trees than on the north, though in this 

 respect the prevailing winds and other con- 

 ditions appear to have an influence. The eggs 

 are deposited quite as readily in the new growth 

 of old trees as in young growth though the dam- 

 age is much more noticeable in the latter. They 

 are placed in small compound groups of from 



r-'ij?. 149 Twig uf apple showing: female 



at work; , t recem e KK punctures; t=--bark s j x to 12 eggs, each arranged in two nearly 



reversed with eggs in position, slightly 



enlarged ; rf=-singie row of e Cgs stiu more p ara llel or slightly curved slits extending in the 



enlarged ; r— wounds of two or three 



years' standing on older limbs, lAtter direction of the twig about 3 t 6 inch, ami sepa- 



Marlatt, U. S. Dep'l Agric. Div. Ent. 1897 



Cir - 2 3. 5.1 rated by x /% inch or less of bark. The bark is cut 



by the ovipositor in such a way when depositing the eggs that the ''narrow 

 portion intervening between the two incisions is loose. This has a very 

 important bearing on the subsequent condition of the wounds made by the 

 insect in oviposition. The object is doubtless to cause a deadening of the 

 wood between the two rows of eggs, and thus prevent their being crushed 

 or choked by the subsequent rapid growth of the twig, and it is due to this 

 peculiarity that the injury later assumes such a serious nature. A single 



