12 N. S. ENTOMOLOGICAL SOCIETY 



out the cocoons in winter; and the Red Eyed Vireo is one of 

 the chief controlling factors in the case of the Fall Webworm. 

 We are all familiar with predaceous insects: the aphis lions, 

 tiger beetles, dragon flies, wasps, ants, lady beetles and so on. 

 A Calosoma beetle is the most important single factor in the 

 control of the Gipsy Moth; and a mite, Hemisarcoptes, is the 

 most important single factor, in Eastern Canada, in the control 

 of the Oyster Shell Scale. 



So much then for a glance at some of the more important 

 factors with which we have to deal in the control of insects. I 

 will now try and show how these factors have operated in the 

 control of two insects, the Forest Tent Caterpillar, and the 

 Fall Webworm. 



In the case of the Forest Tent Caterpillar there was a gen- 

 eral outbreak in New Brunswick in 1913; it lasted only two 

 years and was finally reduced in a single week to a condition 

 of great scarcity. The table shows the fate of a typical egg 

 mass laid in 1912. 



TABLE 2. 



History of average egg mass of the Forest Tent Insect, 

 M. disstria, in New Brunswick 1912-1913. 



chicadees, mites, etc. 25% leaving 150 eggs 



egg parasitism 10% 135 



starved in 1st stage 50% 67 . 5 larvae 



ants in 2-4 stage 75% " 16.9 



parasitized by Rogas 40% " 10.2 



" Exorista30% " 7.1 " 



Blepharipeza40% " 4.2 " 



Pimplas,etc. 65% " 1.4 adults 



These things together brought about a decrease of about 

 thirty per cent. In 1914, however, there was no starvation 

 and no predatism by ants, and consequently a great numerical 

 increase took place. In the spring of 1915 there were eggs 

 enough on the poplar trees to bring about wholesale defoliation; 

 this, however, never took place. The eggs hatched well, but 

 when the laryae were still in the first stage a light frost occurred 

 generally over the province. This had the effect of killing 

 practically all the larvae — countless millions of them. Al- 

 though the frost killed nearly all the larvae, however, it did 

 not kill any of the parasites, so that these became relatively 

 abundant. They were so abundant in fact, that all the larvae 



