150 ' THE ZOOLOGIST. 
were favoured having undoubtedly aided the development of the 
larve. The eggs are usually deposited in the terminal shoots of 
the lower lateral branches; the larve do not, as a rule, devour 
the fresh green growth of the year, but commence to eat the 
foliage on the growth of the previous year, feeding their way 
towards the axis of the tree; very exceptionally I have known 
the new foliage of the year devoured. When in the younger 
stages the larve feed in clusters, but as they grow older this 
trait is not so n.arked, no doubt because each caterpillar requires 
more food. On being disturbed, a characteristic position assumed 
by them is obtained by holding on to the branch with the 
thoracic legs and elevating the abdominal portion until the 
posterior part of itis over the head. When full-fed they drop 
from the branches, and usually spin their cocoons under the 
leaves and grass beneath the tree, not entering the soil. I have 
found them in another situation, i.e., under large stones, down 
the sides of which the larve had evidently crept. From under 
one stone, about a foot square, I have taken as many as twenty- 
five cocoons. 
Nematus erichsoni, the appearance and habits of which have 
just been described, was not known to occur with any frequency 
in this country previous to the commencement of the present 
century. In the last few years, however, it has been found to 
be present in such alarming numbers, in various districts, that 
the Board of Agriculture and Fisheries has placed this sawfly 
among the dangerous insects scheduled under the Destructive 
Insects and Pests Order, the presence of which on any planta- 
tion must be at once reported to the Board. Every occupier, on 
whose land the insect is found, is bound to report the discovery 
under a penalty of £10. 
That the matter is serious is obvious from the following 
quotation :—‘‘ During several extensive outbreaks [of N. erich- 
sont] since 1880 it has killed from 50-100 per cent. of the 
mature larch over vast areas in the North-eastern United States 
and South-eastern Canada. It is evident that the amount of 
merchautable-sized timber that has died as the result of de- 
foliation by this insect will aggregate many billions of feet.’’* 
* U.S. Department of Agriculture. Bureau of Entomology. Bulletin 
No. 58, p. 60. 
