FRIENDS AND FOES OF THE CONIFERiF.. 51 



check enemies too small, or too well protected, to be dealt with 

 by ordinary methods. 



Four woods, situated in various parts of the country, have 

 formed the field of my observations. The first of these is a 

 mixed pine and larch wood, although it contains a little alder 

 and birch. The second, in its lower levels, contains larch and 

 alder in approximately equal quantities, but higher up, the 

 alder is replaced by Scotch fir and spruce. The other two are 

 purely coniferous, and contain only spruce, larch, and Scotch fir. 

 The trees in the first wood seem never to have had a reasonable 

 chance of flourishing, for, at the very first, the larches were 

 planted too closely together; and, instead of being strong healthy 

 trees, becoming stronger with each thinning out, they have 

 become sickly, and simply invite the hordes of insect pests they 

 have succeeded in attracting. When I first commenced my work 

 in this wood seven years ago, both pines and larches were 

 attacked by sawflies ; the larch by the Larch Sawfly {Nematus 

 {LygcBoncmatus) erichsonii) , and the pines by the Pine Sawfly 

 {Lophyrus pini) ; but both of these at the present time, although 

 not exterminated, are negligible quantities, for the attacks of the 

 ichneumon Mesoleius aulicus, and, more particularly, the ravages 

 of a white fungus in the soil, have destroyed them in myriads. 

 Helping these agents too, during the winter, are the various 

 ground beetles, belonging to the Carabidae, and also field voles. 

 Unfortunately, these enemies are no " respecters of persons," 

 and they attack and destroy parasitised cocoons as well as those 

 containing sound larvae ; and it is, therefore, just possible that, 

 when the parasitic ichneumons are becoming powerful enough to 

 cope with the pest, they do more harm than good. It would, 

 therefore, be better to beat the larches when the larvae of 

 Nematus erichsonii are about to descend, and to allow the larvae 

 thus obtained to pupate under artificial conditions. As the saw- 

 flies and any super-parasites emerged they could be destroyed, 

 whilst the ichneumons could be liberated in the woods to 

 continue their good work. 



The sawflies were aided in the work of destruction by shoals 

 of lepidopterous larvae, chief amongst which were those of 

 Coleophora laricella, Phigalia pedaria, Gonodontis hidentata, 

 Hybernia marginaria, and Oporabia autumnata. All of these, 

 with the exception of //. marginaria^ were of sufficient import- 

 ance to need special attention, but a succession of wet seasons 

 has thinned out all except G. laricella and P. pedaria, both of 

 which, especially C. laricella, do untold damage, and therefore 

 demand treatment. Just after the young needles are put forth 

 the hybernated larvae of G. laricella burrow into them and injure 

 them to such an extent that I have seen thousands of trees early 

 in June looking as if blighted by frost. The pines, too, suffered 

 from the attacks of Panolis piniperda, the larvae of which could 

 be beaten out in hundreds. It, too, is gone. 



