52 TRANSACTIONS OF ROYAL SCOTTISH ARBORICULTURAL SOCIETY. 
in clusters, should be squeezed in a gloved hand or rubbed off 
the shoots into a small hamper; or badly infested shoots could 
be snipped off or cut through and dropped into the hamper. 
The contents of the hamper are then emptied on a slow-burning 
fire. This measure, practised against the pine sawfly, will often 
be quite impracticable against the caterpillars of the large 
larch sawfly, feeding as these do, out of reach. 
3. Jarring, so as to shake down larve, would meet with 
most success on a dull day or early in the morning, when the 
caterpillars are cold and sluggish. 
4. Where the caterpillars are out of reach, and the tree attacked 
is isolated, or where the infestation is limited, the trees should 
be sprayed with helebore, or Paris green, or arsenate of lead. 
5. When infested trees are felled, the dislodged caterpillars 
should be destroyed. 
6. There is a certain amount of help from nature. Birds may 
take the caterpillars; in the Dodd Wood rooks and jackdaws 
were seen to be feeding during July on the caterpillars. 
Parasitic ichneumon flies are active enemies of the caterpillars. 
7. The cocoon stage comes within reach of practicable treat- 
ment if the infested area be not too wide. The litter and 
surface soil below trees that were attacked could be ploughed 
in deeply so as to bury the cocoons, or, in a prescribed area, 
boys could be employed to collect them, or the soil and litter 
and moss could be collected together in little heaps. If quick- 
lime were placed on these and water sprinkled over them, the 
heat engendered would kill the enclosed caterpillars. Swine, 
useful in some insect infestations against pupz in the soil, are 
not employable here, as they refuse to eat the cocoons. 
DESCRIPTION OF FIGURES. 
Fig. 1. Mematus Erichsoni (magnified). 
Fig. 1A. Mematus Erichsont (natural size). 
Fig. 2. Larva. 
Fig. 3. Excrement of larva. 
Fig. 4. Two cocoons, each magnified 14 times. 
Fig. 5. Larve on twig of larch; on one of the needles a moulted skin 
is seen, 
Fig. 6 Some injured leaves (magnified). 
Fig. 7. Larch twig defoliated by the larvee. 
Fig. 8. Larch twig, drawn in September, that had been defoliated and 
now putting out new leaves. 
Figs. 1 and 1A after Packard; all the others drawn from nature. 
