658 



Large Larch Saw-Fly. 



[dec, 



group of Ichneumons — the Tryphoninae. The head is black 

 except in the male, in which the facial region is yellow. The 

 antennae, which are long and 34-jointed, are black, as also is the 

 rest of the body of the insect. The first and middle pairs of 

 legs are uniformly coloured yellowish brown. The basal 

 joints of the third pair of legs are resinous brown, the tip of the 

 third (femoral) joint being black, the rest of the leg from 

 about the middle of the fourth (tibial) joint is also black. Its 

 length is 9 -5 mm. (about f in.) and the breadth across the 

 wings is 17 mm. (almost ±± in.). 



Dipterous Larva. — Two specimens of the larva of a species 

 of Dipteron were obtained from the larvae of N. erichsoni. As 

 no mature insects of this parasite were obtained it is extremely 

 difficult on account of our scanty knowledge of the larvae of 

 Diptera to identify even the genus. I believe, however, that 

 they are Tachinidae belonging to the sub-family Sarcophaginae. 

 They appeared to be mature and measured 10 mm. in length. 



Remedial and Preventive Methods. — In combating a pest of 

 this nature, where large areas of mature trees, growing chiefly 

 on mountain and fell sides that are difficult of access, are 

 attacked, we are faced with enormous difficulties. In the 

 first place many of the methods usually suggested against such 

 insects, although they may be suitable for isolated trees of an 

 ornamental character or small groups of trees, if they are not 

 quite impracticable on a large scale, entail a greater expense in 

 their execution than the value of the timber will allow. 



It was found that the method of burning the litter and turf 

 which surrounds the bases of the trees and contains the cocoons 

 though very efficacious was much too costly, even where the 

 plantation was fairly accessible. 



The plan of jarring the trees suggested by Packard is not 

 to be recommended as I have already mentioned, unless the 

 larvae be caught in outstretched sheets beneath the trees and 

 subsequently burnt. 



Where plantations of young trees are attacked it is easier 

 to take active measures. Spraying with arsenite of copper is 

 effectual and has the advantage of being cheap. A pound of 

 arsenite of copper is dissolved in 150 gallons of water ; from 

 4 j:o 6 quarts of flour are mixed with the solution to make it 

 more adhesive to the foliage, the flour being put into the 



