DAMAGE CAUSED BY ANIMALS. 183 



86. The Sprite-shoot Tortrix or Shoot-twister, Tortrix (GrapJiolitha) 



pactolana. 



This is a small moth, having olive-brown upper wings with 

 white markings, and dark-grey hind wings with a light-coloured 

 edge. The caterpillar is of a pale-reddish colour, with a light- 

 brown head. 



The moths swarm about the end of May or the beginning of 

 June, the female laying her eggs in little clusters on the whorl- 

 shoots of young Spruce about 10 to 25 years of age. After about 

 14 days the caterpillars make their appearance, and bore through 

 the soft rind into the cambial layer, in which they form a broad, 

 irregular gallery ; within this they shelter themselves against the 

 resinous outflow by means of spinning a cocoon-like tube. 

 Towards the end of April or the beginning of May, they enter 

 into the pupal state of rest under the bark. 



The presence of this insect is always betrayed by the excrement, 

 which is visible mixed up with the resinous exudation from the 

 wound made by the caterpillar. When several caterpillars are 

 feeding about the same locality, all the portion of the plant lying 

 above the part attacked usually dies off, so that when attacks 

 take place from a large number of caterpillars, the damage 

 inflicted can be by no means inconsiderable. 



The only method of preventing numerical increase of this little 

 enemy is to cut out and burn the young Spruce infested, a 

 measure which is rendered all the easier by the fact that it is 

 principally the plants near the edges of the thickets that are 

 largely attacked. Altum also recommends the smearing of 

 patent viscous tar over the places attacked, in order to prevent 

 the moths from making their exit from the pupal chamber. 



The curious observation recorded by Professor R Hartig may 

 be noted here, that the fungus Nectria curcubitula, which occasions 

 a cankerous disease of the bark on Spruce growth of 5 to 15 feet 

 in height, frequently effects its entrance by means of the places 

 where the bark has been injured by this caterpillar. 



The dark Spruce-shoot Tortrix, GrapJiolitha duplicana, is in 

 colour, life-history, and sylvicultural importance very much like 

 G. pactolana ; but it makes its appearance about four weeks later, 

 and is of less frequent occurrence. 



