398 



The Larch Shoot Moth. 



[OCT., 



June. The eggs are laid then on the lower part of the shoot of 

 the year, one egg being laid for each shoot chosen. The egg soon 

 hatches. At the time the caterpillar hatches out and starts 

 feeding, by boring below the epidermis, the new larch branch is 

 still '"developing, and the feeding of the caterpillar at this early 

 stage is not sufficient to prevent the shoot reaching its normal 

 length. As the year goes on the damage is greater, owing to the 

 increased size of the caterpillar and its more extended feeding, 

 Winter overtakes the caterpillar before it is full-grown, and 

 hibernation takes place in the boring it has made. The 

 borings or galleries are partly filled with black excrement and 

 bore-meal. 



In late March or in the month of April the caterpillar starts 

 feeding again, destroying right to the wood and ringing the 

 shoot to an extent — in the longitudinal direction — of four-fifths 

 of an inch. The twig dies above this place of ringing. 



The caterpillar is full-fed in May, and previous to its pupation 

 it bites a hole through the bark that will serve as a place of 

 exit for the adult moth when pupation is over. This flight- 

 hole is very small. After making the hole the larva spins 

 a light web, which covers over the little hole, and pupates. 

 The moths issue in May and June — my own specimens issued 

 early in June. 



The empty pupal covering does not, as is the case with some 

 moths whose caterpillars are branch-borers, show itself pro- 

 jecting from the flight-hole, but the moth itself when ready 

 works or pushes its way through the web covering the flight- 

 hole, and so to the outside. 



Result of Damage and Signs of Attack. — In the spring of the 

 second year the attacked shoot fails to develop its buds, and 

 remains brown and withered and without needles. Occasionally 

 the dwarf shoot just above the flight-hole may produce under- 

 sized needles. As the shoot is most markedly eaten in the 

 neighbourhood of the flight-hole, breaking takes place here 

 easily, and these broken, bent-over shoots mark the infestation. 



Treatment. — The treatment that follows from a review of the 

 life history is to break off the shoots and destroy them before 

 the escape of the moths. Unfortunately no outflow of resin or 

 appearance of excrement at the exterior is noticeable at the 

 place of infestation (marks which in other insect enemies of 



