400 



WEST VIRGINIA EXPERIMENT STATION. 



gallery. 



beetles after their work of excavating the brood 

 galleries has been completed. 



Egg cavities, Fig. LXV, are excavated in both 

 sides of the galleries at irregular intervals of from 

 one-eighth to one or more inches. 



Larval mines. These extend at right angles 

 from the brood galleries, and vary greatly in size 

 J and form. The normal form is shown in Fig. LXVI. 

 brood and an abnormal form in Fig. LXVI11. The 

 fact that they extend through the outer as well 

 as the middle 

 and inner lay- 

 ers of bark, 

 prevents any- 

 thing like re- 

 gularity in 

 form 



Fig. LXVI. Gallery and larval mines of Dei 

 38 Ob- droctonus frontalis, normal. 



o 



Fig. LX VIII. Gallery of Dendroctonns frontalis, showing 

 abnormal larval mines. 



Fig. LXVIL Nor 

 mal larval gallery 

 of Dendroctonus 

 frontalis. a, exit 

 of larvae; ft, egg 

 cavity. 



served in the 

 inner surface 

 of the bark. 



Pupa cases. 



Width, 1-5 mm; length, 4-5 mm. These 

 are usually in the outer, corky bark, but 

 ma}* occur in the widened larval mines 

 in the inner bark. The normal position 

 however, appears to be in the outer 

 bark as reprecented in Fig. LXIX. 



Brood exits. Diameter, 1 to 1.6 mm., 

 occur promiscuously through the bark 

 and in the surface exposed to view, and 

 resemble shot holes. They extend 

 direct from the pupa cases to the surface. 



Hibernating burrows. These haye^^j^'"^ 

 not been observed but evidently occur in barkof P lne - 



