122 PROTECTION OF WOODS AGAINST 



men might crush the larvae with gloved hands, or the infested 

 shoots could be cut off and burnt ; otherwise the ordinary 

 rule of keeping the woods healthy and clean, and of protecting 

 birds, must be depended upon. 



The large larch sawfly (Nematus Erichsoni). 



This insect has recently done serious damage in the south 

 of Scotland, Cumberland, and Wales, and appears to be so 

 destructive that it has been placed on the list of insects which 

 must be reported to the Board of Agriculture under a penalty 

 of ,10. The woodman should obtain leaflet 186, and also 

 a memorandum issued by the Board. The sawfly measures 

 | inch and is, on the whole, black in colour. The caterpillar 

 measures f inch, and has a black hairy head, a greenish body, 

 with twenty legs. The caterpillars eat the needles of larch in 

 July and August, and may completely defoliate the trees. 

 They prefer trees from twenty to seventy years of age. This 

 makes it difficult to carry out any remedial measure, as the 

 caterpillars are out of reach. When they appear on small 

 trees they should be squeezed in a gloved hand, or infested 

 shoots may be cut off and burnt. On dull days the trees 

 might be jarred to bring down the caterpillars. Full details 

 about this pest will be found in leaflet 186. 



Hemiptera (Plant lice and scale insects). 

 Spruce gall aphis (Chermes abietis). 



This very small insect produces a gall, somewhat like 

 a small fir cone, on spruce twigs. These galls are at first 

 soft and green, but afterwards become hard and brown ; they 

 are usually on one side of the twig, which becomes curved and 

 stunted. Young plants of spruce may suffer considerably if 

 there are a great number of galls on them ; though, fortunately, 

 the leading shoot is seldom attacked. It is believed that one 

 generation of this insect appears on the larch in the form of 

 the larch aphis, and it is therefore all the more necessary to 



