COLEOPTERA SCOLYTID.E. 



123 



I 



v 



Fig. 119. Markings of Pity- 

 ogenes bidentatus (initial 

 stage). 



PiTYOGENES BIDENTATUS (Hei'bst.) 



Pityogenes bidens (Fabr.) 



This is a common beetle, but, being small in size, is very apt to 

 be overlooked. Its breeding-places may be broadly divided into two 

 classes viz., on small dead fir-branches, 

 and on sickly trees, say from 18 inches 

 and upwards, which have been trans- 

 planted in the nursery - lines, or those 

 which have been transplanted in young 

 woods. 



As regards the former class of food- 

 materials, and as forming a commence- 

 ment in the study of its life-history, it 

 may be looked for amongst the small 

 branches of Scots pine, chiefly on the 

 under side of the branch, either "where 

 trees have been felled during the previous 

 winter, or on branches which have been 

 broken off by the wind. The small bore- 

 holes, together with the frass, reveal the 

 abode of the insect. If the thin bark be 

 removed carefully, we may find a star- 

 shaped marking, as in fig. 119. This is 

 a typical beginning of the markings of 

 this species. The central portion is scooped 

 out by the male, where several females, 

 generally from four to six, assemble, and 

 after copulation each female makes her 

 own gallery. The larva?, arising from each 

 respective female make their own par- 

 ticular design of markings, and this con- 

 fusion gives rise to various irregular de- 

 signs, such as shown on fig. 120. The 

 same branches may harbour beetles the fol- 

 lowing year, but the markings are always 

 best followed in recently cut branches. 



As regards the sickly trees infested by 

 this insect, the principal damage is to pines, large transplanted 

 Douglas firs, and so on. The transplanting of such class of trees, 



Fig. 120. Fvlly developed urn fir- 

 ings of Pityogenes bidentatus. 



