75 



winter in the larval form, and it is not until the following spring that the pupal stage is 

 attained. This is the case with most, if not all, the Tenthredinida? which pass the winter 

 in a cocoon. 



The perfect insect is a handsome Saw-Fly, in general appearance, as to shape and 

 size, somewhat resembling the well-known Gooseberry Saw-Fly (Nematus ventricosus) ; but 

 it is slightly larger and quite different in colour. The head and thorax, as well as the 

 nine-jointed antenna?, are black, together with the base and tip of the abdomen ; segments 

 two to five and part of the upper and the whole of the lower surface of segment six, are 

 of a rich waxy orange colour ; the first and second pair of legs yellowish, the femora a 

 little darker than the rest of the legs and slightly tipped with black above, and the 

 third pair of legs is much longer than the others; the femora are a little darker, about 

 the same colour as the abdomen, more decidedly tipped with black above ; the tibia? are 

 light-yellow for two-thirds of their length, and from that spot to the ends of the legs the 

 colour is black. In the other two pairs of legs the tarsi and claws are yellow like the 

 rest of the leg. The wings are black-veined, with a tawny fore margin on costa ; the 

 dark spot towards the tip of the wing, known as the stigma, is black, and there are only 

 three sub-costal cells in this species. The perfect insect is a handsome Saw-fly, the 

 wing of the female expanding about three quarters of an inch, the antenna? are long, 

 over half the length of the body, which latter measures about half an inch. Perfect 

 insects emerge towards the end of June or in the beginning of July, the date varying 

 according to the locality. The eggs are laid in the terminal young shoots of the 

 tamarac, and sometimes in one of the lateral shoots as well. I was not fortunate enough 

 to observe the process of oviposition, nor indeed to find the unhatched eggs ; but in the 

 last Annual Report of the Entomologist to the United States Department of Agriculture, 

 Dr. Packard has published a most interesting report on this insect with a beautiful 

 coloured plate. In this report he describes the manner in which the eggs are laid, as 

 follows : 



" The female saw-fly makes about a dozen incisions in the terminal young, fresh, 

 green shoot, sometimes in one of the side shoots next to the terminal one ; judging by the 

 shape of the hole, the eggs are of the shape described by Ratzeburgh, i.e., oval cylindrical, 

 and about 1. 5m.ru. in length. The eggs are placed in two rows, alternating, not exactly 

 parallel, one being placed a little in advance of the other. The eggs are inserted at the 

 base of the fresh, soft, young, partly-developed leaves of the new shoots, which are usually 

 by June 20th to 30th, only about an inch or an inch and a half in length. The presence 

 of the eggs causes a deformation of the shoot, which curls over, the incisions being in 

 all cases observed, on one (the inner) side of the shoot. * * * * After the 

 foregoing lines were written, we fortunately observed a female in confinement, June 29th, 

 while engaged in the process of ovipositing ; we should judge that the operation of sawing 

 the slit and depositing the egg required not less than five minutes, and perhaps not much 

 more than that length of time. The fly had been evidently at work some time previous, 

 as a number of eggs had been laid along the shoot ; she had begun at the further end 

 and worked down to the base of the new, fresh, green shoot. She stood head downward 

 while engaged in making the puncture, and was not disturbed by our removing the larch 

 twig from the glass jar and holding it in our hand while watching the movements of the 

 ovipositor under a Tolles triplet. The two sets of serrated blades of the ovipositor 

 were thrust obliquely into the shoot by a sawing movement ; the lower set of blades was- 

 most active, sliding in and out alternately, the general motion being like that of a hand- 

 saw. After the incision is sufficiently deep, the egg evidently passes through the inner 

 blades of the ovipositor, forced out of the oviduct by an evident expulsive movement of 

 the muscles at the base of the ovipositor. The slit or opening of the incision, after the 

 egg has passed into it, is quite narrow and about 1| m.m. in length. While engaged in 

 the process the antenna? are motionless ; but immediately after the ovipositor is with- 

 drawn, they begin to vibrate actively, the insect being then in search of a site for a 

 fresh incision. * * * * Although the slit is at first closed, as soon as the embryo 

 increases in size the twigs swell where they have been incised by the ovipositor, and the 

 slits enlarge and gape more or less, becoming much larger and more conspicuous than 

 when the eggs are first deposited." 



