PINE SAWFLY. 
75 
outright. Where the Aphis and Sawfly both attack the same tree I 
think it is generally fatal.” 
The development of Sawfly caterpillars ns subject to extraordinary 
variety, both of date of the time when they leave off feeding and of 
duration of time before they develop into Sawflies, which may occur 
in two or more years after that in which they went into cocoon. The 
following quotation from the « Forst Zoologie ’ of Dr. Bernard Altum 
gives a clear account of the dates of change when the broods take place 
in one season :— 
“ The Sawflies are found at two different times in the year—in 
April and July. Larvas are found in May and June, when they feed 
on the Pine leaves of the previous year. They turn to pupae in the 
beginning of July, and after two or three weeks develop into Sawflies 
(or in August or September). The larvae from these live on the Pine 
leaves of the present season, and (quite differently to the first set, 
which form their cocoons on twigs or Pine leaves, &c.) these go into 
cocoon in the earth. Here the caterpillars he in cocoon the whole 
winter through without becoming pupae until spring, a period of 
nine months for the metamorphoses, which happened so quickly 
previously. 
“However, all winter cocoons do not belong to the caterpillars of 
the second generation ; it often happens that there is only one genera¬ 
tion, and the caterpillars of this hybernate in the ground in cocoons.”* 
There may be difference in detail, as, for instance, the second set 
of caterpillars feeding to some extent on the old Pine leaves, as well 
as those of the previous season, or going into cocoon under moss or 
surface-rubbish; but the above quotation gives a good description of 
the general history where there are two broods, and agrees well with 
Mr. Cattley’s observations. 
The knowledge that when there is a sudden disappearance of the 
Sawfly caterpillars in July, that it is very possible they will be found 
in cocoons on the twigs or on heath or low-growing plants beneath the 
infested trees, may be made very serviceable. The cocoons may be 
pale grey or black, or drab, about a quarter of an inch long, and of a 
blunt oval or rounded shape, and if the heath, or whatever it may be 
on which the cocoons are formed, is cut and burnt, a large part of the 
second brood would be destroyed. If the caterpillars instead should 
have gone under surface-rubbish, this might, as before noted, be 
gathered up and collected in heaps and burnt. 
* ‘ Forst Zoologie,’ von Dr. B. Altum ; Insecten, Part ii., p. 269. 
