386 



" The larvae leave the trees when full fed and spin cocoons in 

 which they live till the spring when they pupate. The cocoons may 

 be looked for under the affected tree not only near the trunk but 

 also over the whole surface covered by the crown of the tree. 

 The cocoons are found in the soil under the moss and litter that 

 usually cover the ground under larch trees and this must be turned 

 back when the cocoons are being hunted for. These are dark 

 brown and cylindrical with rounded ends, and about half an 

 inch long. 



" The adult Sawfly on emerging from the coccon, after the 

 pupal stage is over, is in general appearance black, with glassy 

 wings. The female flies at once to the lower branches of the 

 tree, to lay her eggs, but apparently much of the life of the insect 

 in this stage is spent on the wing and round the upper branches. 

 It can therefore easily be overlooked and is difficult to identify at 

 any distance. The Large Larch Sawfly is nearly twice as long as 

 the Small Larch Sawfly and can be distinguished from the latter 

 which is quite black by the red segments of the abdomen. 



" Larch plantations that are suspected of having been attacked 

 should also be examined with the object of discovering traces of 

 infestation. This work may be carried out from the middle of 

 June to the end of November. The symptoms to be looked for are 

 as follows : In June and July a search should be made on the ter- 

 minal shoots of the branches for signs of eggs, which are laid 

 alternately in two rows. The number is usually about twenty, but 

 as many as forty have been found. The easiest sign, however, to 

 notice, is the distortion of the current year's shoots, which often 

 curl up when eggs have been laid in them. A closer examination 

 will generally reveal the incisions made by the Sawfly's ovipositor 

 on the concave side of the curled shoot. The slits where the eggs 

 have been laid resemble small eyes, less than one-tenth inch in 

 diameter. A little later, in July and August, the needles should 

 be examined for signs of feeding. The young caterpillars do not 

 eat the whole needle but bite pieces out of the edges of it At 

 a later date when the caterpillars are more fully grown, and separate 

 in search of food the whole rosette of needles will be eaten or 

 only a stump left. In August and September these defoliated dwarf 

 shoots may sprout again, and present almost the same appearance 

 as they did in May, except of course that the growth is irregular. 

 These indications are to be found in varying intensity on all trees 

 that have been attacked, but in the case of a serious infestation 



