FAMILY SCOLYTIDAE 571 



The above describes the life history of one generation or life-cycle of the 

 insect, but does not account for the life of the species throughout the year. 

 It has been found that it passes through several generations in a year, 

 the actual number depending upon the climatic conditions of the early 

 and late parts of the season. 



My observations, carried over a series of ten consecutive years, tend to indicate that in 

 ordinary years the insect passes through three to four generations (the last a partial one) 

 in the course of a year, as follows : 



GENERATION I. 



4th week in April . Eggs 



ist week in May to ist week in June ... . Larvae 



ist week in June to end of June Pupae 



3rd week in Jure to ist week in July ..... Beetles 



GENERATION II. 



4th week in June ......... Eggs 



ist week in July to ist week in August . . . Larvae 



ist week in August to 3rd week in August .... Pupae 



2nd week in August to 4th week in August . . . Beetles 



GENERATION III. 



3rd week in August ........ Eggs 



4th week in August to 4th week in September . . Larvae 



4th week in September to 3rd week in October . . Pupae 



2nd week in October to 4th week in October . . . Beetles 



GENERATION IV (a partial generation . 



3rd week in October Eggs 



4th week in October to 2nd to 3rd week in April of the 



following year .... .... Larvae 



(Most of these larvae will be overwintering larvae.) 



If beetles of this generation mature it will probably be from eggs laid in the ist or 

 2nd week of October, when the generation would be as follows : 



ist week in October Eggs 



2nd week in October to 2nd week in November . . . Larvae 

 2nd week in November to 4th week in November . . Pupae 

 3rd week in November to 3rd week in April of the follow- 

 ing year ...... ... Beetles 



(These beetles will hibernate; in the thick outer baik of old standing trees.) 



S. major is a most dangerous pest to the deodar, anil is, as far as is at 

 present known, one of the worst insect foes the tree has 



Damage Committed in to conten( j w j tn _ Trees of all sizes are attacked by the 

 the forest. 



beetle, from the largest tree in the forest to the smallest 



sapling. It usually confines its attacks to sickly trees and trees broken by 

 snow or from other causes, in ;ill of which the vitality h;is become lessened 

 and the upward flow of sap consequently decreased ; it also invariably lays 

 its eggs in newly felled unbarked trees when such are available. In forests 

 where such trees are not available or where circumstances have favoured the 



