176 The Farm Woodlot 



last two abdominal segments. The pupa is nearly white, 

 of the same size and somewhat the same form as the adult, 

 but without free legs and wings, and is found in oblong 

 cavities in the bark where the broods develop. 



The insects hibernate in the bark in the form of adults 

 and larvae, the eggs and pupae cannot stand the cold 

 from October to the first week in June. Activity then 

 commences ; the mature larvae change to pupae and the 

 adults lay their eggs in about twenty days, ten more and 

 the larvae hatch, thirty more and the larvae are mature. 

 In eighty days from the time activity commences, the 

 first adults develop. They continue to develop till the 

 last of September, but continue in the bark till activity 

 ceases. Thus the insect spends eleven of the twelve 

 months in the bark and is dormant seven and a half out 

 of that eleven. 



The evidences of work are much the same as those in 

 the case of Dendroctinus ponderosa. Pitch tubes are 

 formed on the bark, fine sawdust is thrown out from the 

 galleries of the larvae, the leaves turn a light gray-green 

 and soon fall off. The twigs turn reddish. One season's 

 work is usually enough to kill the tree, unless the attack 

 is confined wholly to one side, for the galleries of the adults 

 and larvae in the inner bark completely girdle the tree. 



All practical remedies lie along the line of carefully 

 directed cutting. The beetles are dependent on the pres- 

 ence of large numbers for their ability to attack living 

 trees. Since most of the beetles are located in the mer- 

 chantable part of the tree, the logging, provided the logs 

 are placed in a pond or peeled, kills large numbers of 

 them and may reduce the number below the point at 



