FRIENDS AND FOES OF THE CONIFERS. 53 



obtained. The branches swarm with spiders, amongst which a 

 "rare" species, Bolyphantes expunctus, predominates. Although 

 considered very rare, in these woods it occurs in millions. It is 

 far from being a typical Bolyphantes, for instead of being a 

 ground spider like its congeners Bolyphantes alticeps and B. 

 luteolus, it lives on the twigs of conifers. Spinning no snare, it 

 spends its life devouring Aphids, although in all probability it 

 will not reject other insects if obtainable. Chief amongst the 

 Aphids beaten with it were Chermes abietis, C. laricis, and 

 Lachnus picece ; the first two in the winged state, and the last as 

 larvae. The adult and subadult conditions of B. expunctus 

 coincide with the assumption of the winged state by Chermes. 

 It seems then that, if colonies of this spider were transferred 

 from woods in which it was abundant to woods infested with 

 Chermes, an enormous quantity of spruce and larch could be 

 saved. I can confidently state that, in spite of the fewness of 

 its recorded localities, this spider occurs in multitudes in most 

 mixed spruce, larch, and juniper woods in the North of Scotland. 

 In a little over an hour I have beaten enough specimens to 

 supply all the arachnologists in the world several times over. 



Struck by the above observations first made in 1908, I have 

 paid special attention to the study of pine wood spiders and their 

 economic value. In the case of those possessing snares, I have 

 examined the contents thereof to see what they preyed on. I 

 was surprised when I examined the woods, in which the trees 

 were in the worst condition, to note that, except for the Micro- 

 theridiids, the spider fauna was a scanty one. A few odd Meta 

 segmentata, Zilla 10-notata, Drapetisca socialis, and Amaurobius 

 fenestralis, composed the " take," but all of the webmakers of 

 these were evidently of great use. The noccose snares of A. 

 fenestralis were full of the wings of aphids, sawflies, and last, 

 but not least, of the elytra of the Pine Weevil (Hylobius abietis), 

 and of the various pine-feeding Scolytids. These useful Arachnids 

 did not compensate for the almost total absence of the larger 

 ground spiders belonging to the Drassida? and LycosidaB and the 

 Epeirids. The cause of this absence was plain. When these 

 plantations were made they were formed on an open moor, 

 which was first fired to clear it of gorse and heather, and then 

 surrounded by a stone wall. In this way all the larger spiders 

 were cleared out, and their reintroduction effectually prevented. 

 The " micros," able to colonise new ground by using their 

 floating strands to carry them, got back again. It was possible, 

 too, for winged insect pests to appear, and, together with those 

 brought in with the trees, to increase and multiply without check 

 until the advent of their enemies in the form of ichneumons, &c. 

 Unfortunately, Coleophora laricella is but little affected by these 

 insects, although one would have expected it to be the first 

 attacked, for its near relative, C. ccespititiella, feeding on the 



