INSECTS INJURIOUS TO THE LARCH. 



oval cocoon of leathery texture in rubbish at the foot of the tree, 

 or in m moss, etc., under the surface of the layer of needles on the 

 ground. In warm countries, and with us in warm seasons, a second 

 brood of flies appear from these cocoons in August and September, 

 and in the autumn their larvae feed up very largely on - the 

 needles of that year, which are then suitable for food, and remain 

 in shelter throughout the winter in their cocoons, not actually changing 

 to pupae till about three weeks before the flight-time. The winter 

 period is always passed in the cocoon by the summer larvae if there 

 is no autumn brood. 



The larvae- can be destroyed by shaking them down on to cloths 

 and there killing them, or they may be crushed in situ, by grasping 

 them with a gloved hand or a wad of tow, or with a metal 

 implement like a pair of scissors, with two large flat blades meeting 

 face to face. They can also be killed by spraying with a solution of 

 hellebore, or sprinkling it on as a powder; but better results would be 

 got by the use of paris-green, as for fruit trees. The objections to the 

 use of arsenic on fruit trees do not apply here, except when there is risk 

 of injury to game. 



The pupae of Lophyrus can be destroyed by raking up the brush- 

 wood and upper layer of needles under the infected trees in the winter 

 with the contained cocoons, and conveying the heap to a spot where it- 

 may be safely burned. A very serious objection to this plan is that 

 it deprives the soil of its natural surface-covering of needles, and if 

 persisted in for a long time it will injure the health of the trees. 

 It should not be resorted to without good cause, and when other 

 remedies cannot be adopted. The removal of brushwood, et<-., as 

 opposed to this covering of needles, is always valuable for the 

 prevention of insects. 



Larcli-nriner. A special form of injury is that inflicted on Larch- 

 needles by the larvae of a tiny moth, Coleoplwra larire/Ia, which lays 

 its eggs at the end of June on the needles of the lower branches of 

 Larches about ten to fourteen years old. The caterpillar mines into 

 and feeds upon the interior of the needle, which becomes dry, yellow 

 and twisted ; it then bites off the tip and detaches the needle about 

 its middle so as to form a tube in which it lives and passes the 

 winter, concealed in a crack or under a bark-scale. In the spring it 

 feeds on the new needles, and enlarges its tube by spinning a fresh 

 needle along its side, biting it off and hollowing out the adjacent 

 surfaces ; in this tube it changes to a pupa, and ultimately to a moth. 

 This insect is common in many English Larch plantations, whose foliage 

 when the attack is bad has a dull withered look which is very 

 conspicuous; it does not kill the tree, but keeps it year after year 

 in an unhealthy condition. 



Practical treatment is difficult ; picking off the injured shoots is very 

 troublesome, and the only successful plan is to remove badly-attacked 

 trees, and burn the foliage before the moth flies in June. It is best 

 prevented by growing Larch in a suitable mixture, and not in pure 

 woods. Special importance attaches to this and other Larch-feeding 

 insects because the wounds which they make probably serve as a twlus 

 for the spores of Larch-canker. 



Pine-shoot Moths. The insects which cause destruction to the shoots 

 of Pines are chiefly the caterpillars of the genus Uetinia and the beetle 



