146 TRANSACTIONS OF ROYAL SCOTTISH ARBORICULTURAL SOCIETY. 



Bracons in the South Kensington collection, or with those 

 described by Marshall, I think it highly probable that the species 

 I have reared is B. hylobii. If so it is a species new to 

 Britain, and in order to be sure of this I have sent specimens for 

 identification to Dr Szepligeti in Budapest. 



The degree of parasitism by B. hylobii on the pine weevil may 

 be of interest. In winter 191 1 I observed no cocoons. In the 

 spring of 191 2, two years after the old crop was removed and 

 presumably in the second year of the beetles' occurrence there, 

 I observed a few cocoons, while in 1913 and 19 14 every third 

 pupating chamber was occupied by them. This represents 

 parasitism in the third and fourth years of the pest of over 30 

 per cent. 



I think I do not exaggerate when I suggest that Bracon 

 hylobii, Ratz., may prove of considerable value in combating the 

 pine weevil, which is every year becoming more and more 

 common in newly-formed plantations, especially in Scotland. 

 The parasite is, in all probability, fairly common where Hylobius 

 is found. The fact that it has hitherto apparently been 

 unrecorded does not imply that it is scarce. The persons most 

 interested in Hylobius, the forester and the factor, are interested 

 only in the adult beetle when it begins its attacks on their 

 plantations, and any measures they may take against it are as a 

 rule confined to the trapping and collecting of the adult. 



As to the possibility of using B. hylobii in combating H. abietis, 

 I have not yet obtained a sufficient knowledge of the former's 

 life-history to make any definite statement, but such observations 

 as I have been able to make lead me to believe there are no 

 special difficulties to overcome. If B. hylobii is fairly or 

 reasonably common, and there is no reason to suppose it other- 

 wise, there should be little difficulty in obtaining batches of its 

 cocoons, or numbers of its larvae to breed from. The larvae of 

 Hylobius, too, can readily be kept alive if they are not removed 

 from the roots on which they are feeding. I have reared several 

 weevils by removing the smaller roots containing their larvae and 

 keeping these sufficiently moist. The parasite itself is easily 

 reared, inasmuch as I bred one batch in an ordinary collecting 

 tube in which I placed a weevil grub as food. 



Out of about 70 cocoons, I have obtained no hyperparasites 

 on the Braconid. This again is favourable. The parasite too 

 is evidently hardy. The plantation from which my specimens 



