60 THE CANADIAN ENTOMOLOGIST. 



6 at c, and this is su]jpcsed to be parasitic upon tiie Syrplni> !arv;r. In 

 Canada, Dr. James Fletcher informs me he has bred Praon cerasaphts 

 and Aphidius Fldcheri, a new species recently described by Ashmead ; 

 while in Delaware, Professor E. Dwiglit Sanderson has bred another 

 species of the genus Ap/iialius, namely, A. lVas/iingto/ie//sis, from the 

 destructive green-pea louse. 



In my field observations I have found the predaceous insects very 

 important factors in the destruction of this plant louse. I have observed 

 four groups of insects at work upon them ; First, and most important, 

 the Syrphus flies; second, lady beetles; third, lace-winged flies; and 

 fourth, soldier beetles. 



Of the Syrphus flies, we bred AUograpta obiii/iia, S.iy ; Syrphus, 

 Americanus^ Weid., and Sp/tcerophoria cyliiidrica, Say. The first named 

 was by far the most abundant and important species. On a farm where 

 600 acres were planted in peas, and where the plant louse totally 

 destroyed 480 acres, the larv;e oi A. obliqna so completely destroyed the 

 plant lice by the second week in June that hardly a si^ecimen could be 

 found. In the language of the proprietor, who owns a large cannery, he 

 says : " 'The last k\v days I packed, the separator sieved out about 25 

 bushels of green worms, which no doubt proves they destroyed the plain 

 lice." These " green worms " were the larvje of A. obliqua, illustrated in 

 Fig. 6. The other two species were not so abundant. 



Of the lady beetles the most important were CocciiicUa ij/iotata, 

 Hippodainia couvcfgens. Megilla maciilata and Cocciiiella sanguiiica. 



rhe larva^ of Chrysopa oculata. Say, were also abundant upon the 

 infested vines. I observed the soldier beetle, Podabrus rtigu/osus, Lee, 

 feeding voraciously upon the plant lice. 



From what I have seen of the ravages produced by the destructive 

 green-pea louse, and our inability to combat it on a large scale, I consider 

 it one of the most important pests on the already long list of noxious 

 insects. Whether it will appear again next year over the same general 

 territory on the field pea remains to be seen ; but I am of the opinion it 

 will not be as destructive as the season just past. The superabundance 

 of Syrphus flies and lady beetles over certain areas will certainly have a 

 balancing effect in nature. 



Mailed February 9tl). 191 



