nrrRODTTCTION. 



sect enemies, and if possible, suggest new ones, it is more espe- 

 cially his province to thoroughly study the habits and trace the 

 development of the noxious species, so as to determine at what 

 period of their existence, and at what time of the year, and to 

 what part of the infested plant, the proper applications can be 

 made with the most effect. For there is a period in the lives of 

 most of our noxious insects, and that is usually, of course, the 

 time of their tender infancy, when some one or other of the com- 

 mon remedies, such as soap, tobacco, lime or ashes, is effective in 

 destroying them, provided only that it can be made to reach them. 



In illustration of the time when such applications should be 

 made, we may take two of the most destructive foes of the apple 

 tree, the Kound-headed borer and the Oyster-shell bark-louse. 

 A single application of soap in the one case, and of soap diluted 

 with water in the other, about the last week of May, or the first 

 week of J une, will be fatal to every insect which it reaches ; 

 whereas the same applications are utterly useless if made at any 

 other time of the year. 



In illustration of the importance of observing, in some cases, 

 the time of day also, in which to make remedial applications, a 

 good example is furnished by the Rose-slug, which hides under 

 the leaves in the day time, and thus escapes our ordinary applica- 

 tions, but comes upon the upper surface to feed in the evening, 

 and is therefore entirely exposed. 



As regards the particular jpart of the tree to which to direct our 

 remedies, a very good example is furnished by some observations 

 which I have been making the past summer, upon the Bark-louse, 

 or more correctly, the Coccus {Mytilaspis) of the pine, which, in 

 this instance, stations itself upon the leaf. It is the habit of this 

 insect, like most others of its family, to become stationary for life 

 after the first few days succeeding its hatching ; and it is the sin- 

 gular instinct of this species for the two sexes to fix themselves 

 upon difierent parts of the tree, the males remaining upon the 

 same leaves upon which they hatched, whilst the egg-laying fe- 

 males, which alone demand our attention, for the most part spread 

 themselves upon the new and terminal foliage. 



These, and many other examples of the above general proposi- 

 tions, will be found more fully elucidated in their proper places, 

 in the following report. 



