14 The Scottish Naturalist, 



order to spin under the earth. But if they have been living 

 on a large tree with rough bark, full of crevices, a goodly 

 number enter these instead, and spin their cocoons in company. 

 By removing the bark of a tree upon which the galls have been- 

 abundant, the cocoons of numberless generations may be dis- 

 covered in hundreds, joined end to end, or packed one above 

 the other. 



The cocoons are rarely spun inside the galls. They are 

 oblong, about ^6-inch in length, and of a coffee-brown 

 colour. The larvae of the last broods remain unchanged in 

 the cocoons until the spring, when they enter the pupal state. 

 After the larvae have spun their cocoons, their bodies become 

 considerably reduced in length, but on the other hand they 

 become much stouter. The colour also assumes a yellowish 

 tinge, and the claspers become almost invisible. 



The pupa is much thinner than the larva, and displays all the 

 parts of the future saw-fly; the limbs are laid along the breast. At 

 first it is about the same colour as the larva, but in a short time 

 the thorax, the head, then the back of the abdomen, and finally all 

 parts showthe colours of the perfect insect; thewings gather con- 

 sistency, the insect then gnaws with its mandibles a round lid 

 of one end of the cocoon, leaves it, and after giving some pre- 

 liminary shakes to its wings, and briskly agitating its antennae, 

 flies away to follow the example of its parent. 



The head of the perfect insect is narrow, a good deal broader 

 than long, shining black, mouth light reddish brown, eyes large 

 and prominent. Thorax broad and well developed, black. Some 

 specimens have the head and thorax slightly pubescent. An- 

 tennae, filiform, a little longer than the abdomen, black. 

 Abdomen, black. The feet are light reddish-brown, the 

 posterior tarsi blackish. Wing scales testaceous ; the wings 

 themselves are hyaline, iridescent. The outer half of the 

 stigmal spot is dark testaceous, inner portion pale. The 

 nervures are light testaceous at the base, darker at the tip. 

 Some insects have the wings darker or paler than others, and 

 the submarginal cells are frequently obliterated. Long corp. 

 1^2-2 lin.; exp. alar. 3^-4^2 lin. 



A variable species, but the varieties run so much into one 

 another that they are not worth describing. 



The saw is light brown, shaped somewhat like a scythe, 



