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points of the enemy, any careful fruit-grower can protect his own trees 

 and slay myriads of larvae, but the effect of his labours on the numbers 

 at large in the district would be infinitesimal. All the hope that the most 

 learned scientists on earth could have held out to the farmer and the public 

 a couple of years ago would have been that the raids would not recur 

 for many years in succession, for their insect parasites and other enemies 

 would get the upper hand before long. 



The part played by insect parasites in keeping these insects within 

 bounds is most important and must not be minimized. A thorough knowl- 

 edge of these useful creatures will save enormous losses to our crops, but 

 so far as ridding us of our last visitation of the tent-caterpillars is con- 

 cerned they cannot be credited with the results. If there had not been 

 such a thing as an insect parasite the results would have been the same. 



The destroyer was a fungous or bacterial disease whose name and 

 nature I know not, but perhaps some of our good friends at Macdonald 

 College have been in a position to make extended studies of the disease 

 that, towards the end of May and early June, 1913, fell upon the larvae 

 and left nothing but their dried and shrivelled skins in myriads on the 

 trunks and branches of the trees, those that were parasitized as well as 

 the others all succumbing. Now comes the problem for the experimen- 

 talists. The caterpillars had only half finished their work of destroying 

 the leaves in the woods and the trees recovered, and by the end of June 

 the foliage looked beautiful and remained so till the fall; but when I and 

 others who occasionally like to collect a variety of caterpillars to study 

 their life-histories and rear in confinement long series of the beautiful 

 moths went forth, lo and behold there were no caterpillars! Time and 

 again we searched but instead of finding some kind every few minutes, a 

 whole Saturday afternoon would produce perhaps three specimens. The 

 fall web worm — that troublesome fellow which makes the ugly webs in 

 the elms in our Montreal streets, was absent, the obliquely striped green 

 caterpillars of the hawk-moths were absent, the large green silk-produc- 

 ing larvae were absent and all the other leaf-eaters were distinguished 

 by their absence. This strange state of affairs is due to a cause, and I 

 suspect the enemy of the tent caterpillars to be at the bottom of it. Can 

 anyone tell us how long it takes for these organisms to develop to their 

 dangerous stage? Is there more than one species, and if so, are they partial 

 to any particular kind of larvae or are they omnivorous? During last 

 summer and fall the scarcity of moths in their usual haunts and absence 

 at artificial attractions such as light and sugar have been noted by all 

 our local entomologists, and again in the fall caterpillars of all sorts were 



