22 



Fig. 16. — Xyleborus dispar .• Male and female 

 iniagos — enlarged, antenna of female more 

 enlarged (original). 



four teeth in each row. According to observations made by Professor 

 Hopkins and Mr. Schwarz, X. planicollis Zimm. is pretty certainly the 



male of X. f meatus. 



The food galleries of 

 this species are excav- 

 ated in many kinds of 

 trees and also in wine 

 casks, but it breeds 

 chiefly in oak, hick- 

 ory, and perhaps other 

 hard woods. 



The "dispar" group. — 

 Three species, X. dis- 

 par Fab. {pyri Peck), 

 X'. tachygraph us Zimm., 

 and X. obesus Lee, 

 exhibit extreme differ- 

 ences between the 

 sexes. The males are 

 very minute. They 

 have the thorax nar- 

 rowed in front and 

 the form excessively 

 abbreviated, so that it becomes oval and convex long- 

 itudinally. 

 The species of this group have the habit of making 

 circular galleries in small 

 branches of healthy trees, 

 ber they form branching galleries, as in the 

 pubescens group. 

 , k\ I iij» Xyleborus dispar Fab. 



(fig. 16) is an extremely 

 injurious insect both 

 in Europe and America. 

 According to Eichhoff 

 it lives in almost any 

 kind of tree, including 

 conifers. In this coun- 

 try its injuries to fruit 

 trees have been noted 

 by many writers, begin- 

 ning with Peck in 1817, 

 who described it, under 

 the name (X.) pyri, 

 as destructive to 

 branches of pear young 

 trees. 



Fig. 17.— Gallery of 

 Xyleborus dispar in 

 Liriodendron twig: 

 Upper figure, trans- 

 verse section ; lower 

 figure, longitudinal 

 section (after Marx). 



In larger tim- 



Fig. 18. — Xyleborus celsus: Female and male— enlarged (origina 



In fig. 17 is shown the gallery which the female makes, encircling the 



