94 



FOREST ENTOMOLOGY. 



doubtless during this initial boring operation that copulation takes 

 place. She then makes her burrow proper, which is from 1 to 

 4 inches in length, and therein deposits from 100 to 160 eggs. 

 This operation is said, as a rule, to take about three weeks to 

 complete. 



The markings are very characteristic, more especially when the 

 mother-gallery is comparatively short. The mother-gallery is straight 

 and single-armed (fig. 84). Taking, therefore, the middle of the gallery 

 .as a centre, it may be noted that the larval galleries do not quite 



Fig. 84. Markings of Seolytus destructor 

 in bark of English elm. 



Fig. 85. Showing " exit- 

 holes" of same. 



run at right angles with the mother-gallery, but point slightly towards 

 the extreme ends ; and as we look towards either end of the mother- 

 gallery, it is noticeable that the angle becomes more acute, and con- 

 sequently the spaces between the extreme ends of the larval galleries 

 widen. Hence if a line were drawn all round the extreme ends of 

 the larval galleries, it would form an oval-shaped figure, with the lines 

 radiating from the centre to the outer edge. Fig. 85 shows the holes 

 whence the beetles have emerged. 



The beetle (tig. 813) is about y\- of an inch in length. The thorax is 



black and shining, and the abdomen light-brown. The beautiful sharp 



contrast of colour is a conspicuous feature, and thus affords a rapid 



