feet in height, aiiove whicli a hoisting apparatus must be used. Tent coi-ers 

 may be used for trees up to 13 feet in height. They talce the form of dome- 

 shaped tents, the mouth of which is Icept open by a riug of gas-piping passed 

 through canvas loops, and they can be quiclvly lifted over and removed from S 

 to 13-foot trees by a couple of men, where the hoisting of a sheet would take 

 three or four. Box covers are made to any convenient size by covering a 

 wooden frameworlv with canvas or calico ; the latter material should be painted 

 or oiled to make it suttieiontly gas-tight. They are especially adapted for small 

 trees and bushes. 



Note. — As both the pota.ssium cyanide and the hydrocyanide acid gas are 

 deadly poisons, the former should be kept in a tightly-stoppered bottle and 

 labelled Poison, whilst the gas as generated must on no account be breathed. 

 Fumigation should not be carried out in a high wind, nor when the trees are 

 wet, but otherwise it may be done at any season of the year. — Board of 

 Agriculture and Fisheries:. -} Wliitehall Place, London S. W., Januarij, 190S. 



CHAPTER III.— BENEFICIAL INSECTS. 



The subject of parasitism among insects is not only a very interesting one, 

 but it is one which, affecting as it does, either directly or indirectly, nearly 

 every species of plant or animal on the face of the globe, has an economic 

 bearing that, in all of its ramifications, is important even beyond our com- 

 prehension. If we look out upon the heavens on a bright summer night, we 

 observe myriads of worlds each of which is rushing with resistless force and 

 almost lightning rapidity along its course through trackless space, yet never 

 colliding or jostling one another. We can only in a vague manner, at best, 

 comprehend the magnitude of this mechanism, or realise the power wliich 

 holds each planet in its proper place, and prevents it from rushing to its own 

 destruction or that of its neighbour. 



In our own natural world, assuming that species are living representatives 

 of what we witness in the heavens, then one of the greatest, if not indeed the 

 most powerful, force which holds each .species in its proper sphere, is that 

 influence which we call parasitism, and but for this influence, puny humanity 

 would scarce be able to live out a miserable existence. As it is, the value of 

 insect friends in combating insect, and I might also add plant, foes, is but 

 little understood, and, in fact, very few of those receiving a direct benefit even 

 know of the existence of their benefactors. 



There are, of course, many destructive insects which are exceedingly 

 abundant every season, but they are such as have been imported and their 

 parasites left behind, or they are such of our native species as a change of 

 environment, brought about by our progress and improvement, has, apparently, 

 enabled to reproduce nnich more rapidly, and hence they have become too 



