26 FIFTH ANNUAL REPORT 



been used; here we see the importance of such applications as lime 

 for slug-worms (genus Selandria) and other larv£e having soft, slimy 

 skins ; of white hellebore for the currant-worms (genus Nematus), and 

 of some preparation having Paris Green as its base, for the Colorado 

 Potato Beetle. As a rule, however, these methods of cure are far less 

 satisfactory in their results than the modes of prevention, and should 

 never be relied on when the latter can be resorted to. 



That of causing them to be killed by encouraging their natural 

 enemies, is one of the most eiFectual methods of counterworking 

 noxious insects. Among such natural enemies, birds, toads, snakes 

 and other reptiles hold a prominent place ; and we have here to treat 

 of the complicated bird question, or what may be termed ornithologi- 

 cal entomology, which is yet in its infancy, and calls loudly for more 

 attention. But the more important enemies of noxious insects are 

 found in their own Class, and consist of the predaceous or cannibal and 

 the parasitic species, wisely ordained to keep the others within due 

 bounds. 



To avail ourselves, in the fullest manner, of the aid of these 

 friends, it is necessary, first, that by observation we discover what 

 particular species prey on a particular vegetable-feeder ; second, that 

 by observation and experiment we determine the cheapest and most 

 convenient method of spreading or propagating the species that so 

 prey upon it; and if, as often happens, there are several such species, 

 to determine which of them can be propagated most readily and 

 cheaply. 



In some cases we can do much to encourage the growth and dis- 

 tribution of our insect friends. Take, as an example, the imported 

 Cabbage Butterfly already alluded to. In searching for insects in the 

 winter time, in England and other parts of Europe, I recollect very 

 well, when a lad, how common the naked and suspended chrysalides 

 were along the ledges of palings and in other sheltered situations; 

 and how a large per centage of them were always parasitized, and 

 generally distinguishable, in consequence, by their discolored look. 

 Now, these could be collected by hundreds in winter time, shipped to 

 this country, and the parasites allowed to escB,pe in some cab- 

 bage-field infested with Pieris rapce. The little Chalcid parasite of 

 the Oyster-shell Bark-louse is easily introduced into "scurvy" 

 orchards not yet favored with it, as I shall show in this Report. The 

 parasites of the Plum Ourculio (3d Rep. pp. 24-9), and those of the 

 Codling moth, to be described further on, are easily bred and dis- 

 patched to parts where they are yet unknown. So of the enemy of 

 the grape-leaf hoppers (3d Rep. p. 137), and of many others. 



But practically, the propagation of a large proportion of parasitic 

 and cannibal insects is beyond man's power; and all we can do is to 

 protect and encourage them, as opportunity offers. To do so, it is very 

 important that we know how to distinguish between our friends and 



