394 



The Large Larch Sawfly. 



[OCT., 



the caterpillars, especially when they are small and, it may be, 

 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 larvae would meet with most 

 success on a dull day or early in the morning when the cater- 

 pillars 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 hellebore, 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 sur- 

 face 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 quicklime 

 were placed on these and water sprinkled over them the heat 

 engendered would kill the enclosed caterpillars. Swine, useful 

 in some insect infestations against pupse in the soil, are not 

 employable here as they refuse to eat the cocoons. 



Description of Figtites: — Fig. i, Neniatus Erichsoni (magnified); Fig. lA, Ne- 

 matus Erichsoni (natural size) ; Fig. 2, Larva ; Fig. 3, Excrement of larva ; Fig. 4, 

 Two cocoons, each magnified i\ times ; Fig. 5, Larvse 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 larvre. Fig. 8, Larch twig, drawn in September, that 

 had been defoliated and now putting out new leaves. Figs, i and lA after Packard, 

 all the others drawn from nature. 



R. Stewart MacDougall. 



