FAMILY SCOLYTIDAE 579 



I have not yet been able to ascertain whether the beetle girdles more than 

 one branch. After laying her eggs she leaves the branch by the hole of 

 entrance, which is usually just above the groove. 



That the young larvae hatch out from the eggs in a few days has 

 been proved from the fact that quite young larvae are to be found boring 

 away from the girdle whilst the cut branch is still fresh and green. The 

 girdle is of course made by the beetle to prepare a sufficiency of food material 

 in the withering condition required by its grubs on issuing from the eggs. 



The larvae on hatching bore straight up the girdled branch (as 

 shown in fig. b) in the cambium and sapwood, eating out slightly winding 

 galleries about one and three-quarters to two inches in length. These 

 larval galleries are blocked throughout their entire length with wood-dust 

 and excrement. 



When full-grown the larva eats out in the sapwood a chamber slightly 

 larger than the gallery, and pupates in this. The beetle on maturing bores 

 its way out by a horizontal tunnel through the bark. 



The life-cycle of the generation from the eggs laid in June or com- 

 mencement of July takes about seven weeks, beetles being obtained in the 

 latter part of August from branches found freshly girdled on 3 July. The 

 larval stage of this generation thus probably lasts from four to five weeks. 



Occasionally it has been noticed that a branch has been girdled in two 

 separate places, whether by the same beetle or not I cannot say. An 

 instance of this is shown in fig. 365, A, i and 2. 



During a tour in the Jaunsar Himalaya in the autumn of 1906 

 (September to middle of November), I found the beetles engaged in girdling 

 branches and egg-laying at the end of October, This proves that there are 

 two generations, or the whole of a first and a partial second, in the year. 

 I am inclined to think that the August beetles lay the eggs of the second 

 generation of the year and that the beetles found in October are from the 

 August eggs. 



The insect is extremely wasteful in its method of ovipositing. Large 

 branches are girdled often two to three feet in length and with several forks 

 or side branches on them. From the whole of this large cut branch but 

 one and a half to two inches are grooved beneath the bark by the larvae 

 as shown in fig. 363, b. The rest of the branch thus destroyed is, so far 

 as this scolytid is concerned, entirely wasted. 



As a matter of fact, however, the upper portions ot these branches 

 are very often infested by a second scolytid, Cvyphalus {Stephanodercs), 

 described on p. 540. 



This Scolytus differs from the other Scolytidae known to infest the 

 deodar in the fact that it makes its appearance very late in the year. 

 I have never yet found the beetles ovipositing before the middle to the 

 third week of June, whereas the other scolytid pests known commence 

 laying the eggs of the first generation of the year towards the end of 

 April. This late appearance may be due to the fact that this insect is 



o o 2 



