188 PROTECTION OF WOODLANDS. 





larvae or caterpillars, which have only three pairs of thoracic 

 legs, and one pair of feet on the last section of the abdomen for 

 purposes of propulsion, live in a cocoon which moves forward 

 with them along the twig ; this cocoon is partly transparent, but 

 most of it is so obscured by pieces of needles, and especially by 

 excrement, that it has been termed the " dung-bag." As these 

 saw-flies only seldom occur in large swarms, and are not under 

 ordinary circumstances particularly injurious in coniferous wood- 

 lands, it will only be necessary to mention the following principal 

 species briefly : 



The Yellow Cocoon Saw-fly, Tenthredo (Lyda) campestris, whose 

 tiny larvae or caterpillars live singly on the young shoots of 3 to 

 6-year-old Scots and Weymouth Pines, and are covered with a 

 thick dung-bag. The chief exterminative remedy applied, when 

 young plantations or transplants in nurseries appear to be 

 attacked, is pulling the shoots firmly through the gloved hand, so 

 as to crush the larvae. Young Weymouth Pine transplants are 

 apt to suffer a good deal from them, but the presence of the 

 caterpillar is easily noticeable. 



The Large or Variegated Cocoon Saw-fly, Tenthredo (Lt/dct) 

 pratensis, whose larvae live singly in sacks that are usually less 

 defiled with excrement than in the other species. It is more 

 frequently to be found on 15 to 40-year-old pole- forests of Pine 

 than on younger growth, so that practical remedies by crushing 

 the sacks containing the small caterpillars are hardly applicable. 



The Red-headed Cocoon Saw-fly, Tenthredo (Lyda) erythocephalciy 

 lives in colonies of 3 or 4 in sacks plastered over inside with bits 

 of needles and excrement. It occurs principally on young Scots 

 and Weymouth Pines, and as it makes its appearance early in 

 May, its attacks are confined to the older foliage. 



The Spnwe Cocoon Saw-fly, Tenthredo (Lyda) hypotrophica, has 

 now and again occurred in Spruce pole-forests in such large numbers 

 as to have cleared them of all the older needles, and in some cases 

 even to have totally denuded them of foliage. Against this species 

 also there is no direct practical annihilative measure applicable. 



