5i8 FAMILY SCOLYTIDAE 



felled will result in an unnecessary loss in the annual income from the forest, 

 the omission to remove trees seriously infested by the beetles will result in 

 greatly lessening the value of the fellings made, and will necessitate further 

 removals of trees in the year or years following. 



The practical effect of the remedies recommended was illustrated in 

 the severe attack of these bark beetles which took place in the Shinghur 

 Forest in Zhob in igoo-1906. Work was begun in the autumn of 1905, 

 and carried on throughout 1906, the Political Officer, Lieut. -Colonel G. 

 Chevenix-Trench, being ably assisted by the Forest Officer, Bhai Sadhu 

 Singh : and the fellings undertaken, combined with the burning of all 

 infes-ted trees felled, practically stamped out the attack. 



My examination of the infested trees in the Takht-i-Suliman area in 

 November 1905 proved that the beetles passed through four generations in 

 the year. From rough calculations made from measurements taken on the 

 ground, it was computed that an average-size i tree in the Shinghur Forest 

 could produce at a rough estimate a generation of 40,000 beetles. Allowing 

 for 50 per cent, casualties, this would give rise by the end of the year to a 

 progenv of 40,000,000 beetles, on the supposition that the insect passed 

 through four generations only during this period. 



From this calculation it follows that the removal of the 92 badly 

 infested trees, and the burning of the bark containing immature larvae, 

 pupae, and beetles, may be safely estimated to have reduced the beetles that 

 w^ould have been present in the forest in the spring of 1907 by some 

 500,000,000, allowing for very heavy mortality amongst the over-wintering 

 larvae and pupae. 



The Polvi^raphits and Phlocosiuiis beetles are subject to the attacks 

 of predaceous and parasitic insect foes, and it may 

 PredaLlfltecTL. 1'= d"« '° 'his fact that the bark-borers have not 

 been able to increase in such numbers as entirely 

 to destroy such a local area of trees as the Shinghur Forest represents. 

 Trees Nos. 3 and 4 were swarming with these active predaceous foes, the 

 insects being found within tree No. 3 and on the bark, and entering tree 

 No. 4. No less than six different kinds were collected, all actively engaged 

 in feeding upon or ovipositing in the galleries of their hosts. It is probable, 

 I think, that one or more of these insect enemies are predaceous upon or 

 parasitic in one or more of the insects predaceous upon the bark-borers. 

 They include two hymenopterous flies, an undescribed species of A' z'/'o;ri»s, 

 two species of Colydiidae, and a species of predaceous bug, the Niponius 

 being perhaps the least abundant of the six. 



The Hymenopterous Flies.— These flies are probably species of the 

 family Chalcididae. They lay their eggs either in or amongst the eggs of 

 the bark-borers, or in or on the grubs. They were to be found nume- 

 rously in the trees, and their grubs evidently do not kill the grubs of 



