390 



The Large Larch Sawfly. 



[OCT., 



what thick, and taper towards the apex. With a lens the head 

 and thorax are seen to be sparsely and finely pubescent, and the 

 thorax is markedly punctured. The wings are glassy and 

 slightly clouded below the stigma. 



Egg. — The egg is longish oval, and measures just over a 

 millimetre in length. It is white in colour. 



Larva. — The full-grown caterpillar measures three-quarters of 

 an inch, or a little over, in length. It has a round black hairy 

 head, with a single ocellus on each side. On the upper surface, 

 all down the back, the colour is grey-green ; the sides are lighter ; 

 the under surface is yellowish-green. If one uses a lens there 

 will be seen on the abdominal segments transverse rows of 

 minute warts with spines. The spiracles along each side are 

 brown. The legs number twenty, viz., three pairs of thoracic 

 legs, which are black, and seven pairs of abdominal legs, which 

 have the colour of the underside of the body. The head is 

 followed by twelve segments or joints — i, 2 and 3 are thoracic 

 joints, and each bears a pair of legs ; 4 to 12 inclusive, are abdomi- 

 nal joints ; 4 has no legs ; 5, 6, 7, 8, 9 and 10 have each a pair of 

 legs ; 1 1 has no legs ; and 12, the last joint, carries a pair of legs. 



Packard* describes the caterpillar as moulting three times, 

 and so distinguishes four stages of larva. On hatching, the head 

 is very large and dusky green, not black ; neither are the 

 thoracic legs black ; the body is uniformly pale green. After 

 the first moult the head and thoracic legs are black : the body 

 is wrinkled, but no warts show. After the second moult the 

 upper surface is grey-green, and the transverse rows of warts 

 appear. The caterpillar attains its full size after the third 

 moult. The moulted skins can be seen wound round or 

 attached to the leaves. 



Excrement. — The castings (excrement) of the caterpillar are 

 longish, cylindrical, and somewhat square cut at the ends. The 

 castings observed on the ground will afford a hint as to the 

 presence of the larvae. So numerous were the caterpillars in 

 some parts of the attacked area that in July their excrement 

 falling on leaves below suggested the patter of rain drops. 



Cocoon. — The cocoon, strong and leathery or parchment-like 

 is dark brown in colour ; it is cylindrical in shape, with rounded 



* Fifth Report of the United States Entomological Commission : " Forest Insects.' 

 1890. 



