59- 



Xi:w YORK SIATF. Ml'SKVM 



color, without inarkinj^s, and cylindric, except as its shape is moditied by 

 pressure of the wood and adjacent e^j^s. The youni( resemble the adults 

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

 i)arl)ed projections. The ailult is a i^rreen insect, about 3 « inch in lent^th, 

 And may be easil\' recognized 1)\- the j^reatK' eidar^jed tliorax which bears 

 on its anterior anL,des lateral projecting; horns, as represented in ti^^ure 148. 

 Life history. ihe life history of this insect has been g-iven by Mr 

 Marlatt substantialK' as follows : 



The adult insect tle|)osits her eggs in twigs 

 of \-arious trees, preferabl\- thost- t)f two or three 

 \cars' growth, particularly the a])]jle, willow, cot- 

 lonwootl, maple etc. ami conhnes its operations 

 in general to the upper surface of the twigs. It 

 works more abuntlaiuly on the south side of 

 the trees than on llu' north, though in this 

 respect the prevailing winds antl other con- 

 ditions appear to ha\e a!i influence. The eggs 

 are depositetl <piite as reatlih' in the new growth 

 of old trees as in \()ung growth though the tlam- 

 age is much more noticeable in the latter. I hey 

 are placed in small compound groups ol trom 



1 14 Mg Iv^i;; of apple hliuwin^: it -fejii.tle 



... u,.rk; /■ reLent egK punciurcs; . -iiarw ^ix to 12 eggs, facli arraugcil ill t WO ucarly 



reversed uilh e^gs in positiun, slightly 



eniargci ;,/. single rnw ..f eggs siiii iiu.rt- |,;j,-;j11,.1 orsHglitlv cui"\'ed slits extending in the 



enlarged ; ^-^ winmds of two or llirrr . ' ' 



years' slaniUng c.n older linil.s. lAller thrCCtioll of tllC twlg ai)OUt -' ,(, iucll, aild Se|)a- 



Marlall. C S. Ilep'l Agric. Div. Km. iKi,; 



CU-. ^i. j,i ■i.) ratetl by 's inch or less of Ijark. The l)ark is cut 



by the o\i|iositor in such a wa\' when tlepositing the eggs that the narrow 

 |)ortioii intervening between th(^ two incisions is loose. I his has a \cry 

 important bearing on the siii)si'(|uent condition of the wountls made b\ the 

 insect in o\iposition. I he object is doubtless to cause ;i deadening of the 

 wood between the two rows of eggs, and thus j)re\-ent their being crushed 

 or choked b\- the subsc(picnt ra|)id growth ol the twig, and it is ilue to this 

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



