50 TRANSACTIONS OF ROYAL SCOTTISH ARBORICULTURAL SOCIETY. 
observed a female in confinement, and thus describes the egg- 
laying :—“ The sawfly 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 movement of the ovipositor.” (This same 
restfulness I have observed in the pine sawfly (Z. pzuz) while 
watching a female in captivity laying her eggs.) ‘The serrated 
blades of the ovipositor were thrust obliquely into the shoot by 
a sawing movement. After the incision was sufficiently deep 
the egg was 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 12 mm. in length. While engaged in 
the process the antenne are motionless, but immediately after 
the ovipositor is withdrawn they begin to vibrate actively, the 
insect being then in search of a site for a fresh incision.” As 
the embryo develops the slits in the shoots gape a little, and 
through the oval hole the caterpillar creeps on hatching. The 
caterpillars may begin by gnawing the single leaves on the 
young shoot, but they soon pass to the clusters of needles on 
the dwarf shoots. Single leaves may be eaten so that the edges 
appear serrated, or the clusters of leaves may be half eaten 
or quite destroyed so that only stumps are left. 
In the young condition the caterpillars may be found in 
clusters. The caterpillars assume various positions, arranged 
with the tail end curled round the shoot; or like a mark of 
interrogation, or the letter S; or (a characteristic attitude) with 
the hind half of the body turned upwards and over the front 
half. On being handled the caterpillars would wriggle violently, 
rolling themselves about in a fashion that reminded one of sur- 
face caterpillars, and ultimately lying on their side with their 
body forming a circle, the tail end touching the head. 
The larve are to be found at work during the summer, and 
most numerously in July and the first fortnight of August. By 
the end of August most have left the trees. Some, however, 
do not complete their growth till September. I kept some in 
confinement that made their cocoons in the second week of 
September. The full fed caterpillars leave the trees and pass 
into the moss or litter or the soil below, and in such shelter- 
places spin the cocoon in which they pass the winter. They lie 
somewhat bent in the cocoon until the late spring or summer of 
