ENTOMOLOGICAL.

Otago Witness, Issue 2009, 25 August 1892, Page 5

ENTOMOLOGICAL.

TREE BORERS.

There are several insects whose larvse bore into the wood of both fruit and other trees, very often doing serious mischief. Not unfrequently they eat out the pith, especially of such trees as have soft wood and large piths. When this is the case it is generally detected by a small quantity of what has been called ' ' sawdust," heaped outside of an oi>ening in the bark. Very often the insect, if not detected at first, will destroy a whole branch, and going dowu that will enter a larger stem, and to get rid of it and let the tree heal up, it is frequently no.:eßsary to remove a large quantity i«f valuable fruit-bearing wood. Mr T. B. Ashton, a fruit-grower of Kansas, after being much troubled with these borers, hit upon a very easy and effectual remedy for them, which he sent to the Department of Agriculture, at Washington. His letter contains the following : — "Quito a number of ways for destroying the larva) of various kinds that live in the bark and sap wood of the apple and other varieties of fruit tre6B have been published, but none of them are as good, in my judgment, as the way I now recommend. I kuow of no better way of effectually putting a stop to their depredations than by using unadulterated kerosene quite freely wherever the castings ('sawdust') of the larvae are seen protruding from the bark. As soon as the kerosene ccmes in contact with these sawdust-like castings it is absorbed and carried by capillary attraction until it permeates the whole burrow and comes in contact with the larvai, and then soon this noted little tenant islif eless. In using kerosene there is no use iv cutting, digging into, or in any way mutilating the tree to find the larvco. The fluid kerosene will find it, and this is enough for practical purposec, and then nature stfps in with her healing art aud mends tno damage done to the tree. Tho amount of the kerosene used is so small that it endangers in no way the health of the tree. A person can visit and inspect many trees in a single hour anil, if necessary, apply the spout of a can and flow a small amount of k^ro-ene in various places. The advantages of killing the borers iv this way are — no mutilation, quick work, sure death, and little expense." This remedy applies best to larvae which bore in the bark and in the soft wood, or sap wood, under the bark. It also applies in cases of the larvse of beetles which eat out the pith, and will be found a perfect cure where the burrows are not too long ; but in this last case it is often necessary to out back a portion of the bored shoot and to inject the kerosene with some foroe with a small syringe. A piece of ductile copper wire if also useful to push into the burrows, and very often it reaches the larvae. The perfect infect lays its eggs gene> rally at (be buds or in a brgken or cut crevice

iv the bark, and the .small larva; eat their way down the pith, and the sooner their action is observed the better and the easier the kerosene

THEIR NATURAL ENEMIES It is singular to observe how all destructive insects have their special enemies which helo man to combat them, and some of these borers' enemies are very curious and interestiu«Amongst them is a species of large iuchneuman fly. It is very active, and runs quickly along the shoots and branches of trees until ib detects in some way the presence of the larva in the pith. Ifc has a curious and very complicated set of boring apparatus, consistiug of a long and very sharp auger, which is hollow and nets also as an ovipositor, at the end of which (next the body) there is a kind of, spiral spring, which presses it onwards. Two learos of the sheaf act as supports to the anger when in u30u 30 The insect, on linding the whereabouts of the borer larva, elevates its body in a peculiar manner, and commences to bore down to it throuch the wood. Having reached the burrow it conveys *n egg into it, and this egg hatches a, maggot which seeks out the borer larva, and attaching itself to its victim by a pair of powerful jaws sucks its life juices and arrives at its maturity at the expense of its so-called host. bometimes, however, this useful little friend of man is found with its auger firmly fixed in the wood and perishes in that situation, probably from exhaustion after layina several eggs. Entomologist.