NOTES ON THE WOOD-WASPS iSIREX) IN SCOTLAND 179 



in their pupal chambers, and these prove the species to 

 have been 5. cyaneus. A feature of the flight-holes, which 

 are about the diameter of an ordinary lead pencil, is their 

 perfectly circular form. This calls to mind an amusing 

 incident which occurred on the railway near Dunbar a 

 number of years ago, when numerous flight-holes were dis- 

 covered on a telegraph-pole, and gave rise to the rumour 

 that some one had been firing bullets into the post. 



{c) Natural Enemies of Sirex in Scotland. — So far as 

 I know Sirex has in Scotland only two natural enemies^ 

 capable of exercising any real control on its numbers ; these 

 are the large Ichneumon-fly, Rhyssa perstiasoria, L., which 

 in its larval stage is a parasite of the Sirex grub ; and the 

 Great Spotted Woodpecker, now a widespread resident bird 

 in Scotland. The latter certainly does not discriminate 

 between the species of Sirex, for, while I have seen dead 

 spruces on the Esk above Polton, which were known to be 

 infested with ^z^^i", vigorously explored and hacked into by 

 a woodpecker, I have observed the same thing in the case of 

 old silver firs at Penicuik from which only the remains of 

 cymieits were obtained. The Rhyssa may be more discrimi- 

 nating, though I can hardly think so. Up to the present 

 however, I have only heard of one instance in v/hich it has 

 been reared from a blue-black species, namely vS, cymieiis 

 (specimens in Perth Museum). On the other hand, of attacks 

 on gigas there is ample evidence. In the summer of 1917 

 Mr G. Lyford Pike showed me many 6". gigas that had 

 emerged from logs in the laboratory of the Forestry Depart- 

 ment of Edinburgh University, and a fair number of Rhyssa 

 that had hatched out of the same logs. Gigas was the only 

 Sirex present. During the same summer I found Rhyssa 

 quite plentiful on two dead spruces in the glen below Haw- 

 thornden, that were known to be infested with the same 

 species. Again, in July and August 1921, Mr K. J. Morton 

 found both gigas and Rhyssa emerging in numbers from a 

 felled pine at Achnamara, Kintyre. 



{d) Early Records. — Whether the ancient pinewoods in 

 the Highlands of Scotland — there were none I gather in the 

 ' Fungoid attacks are not here taken into account. 



