392 C. H. TURNER 



wintering period as the usual occurrence in northerly latitudes. 

 In no case have I been able to find in England or Canada living 

 pupae of Musca domestica, under outdoor conditions, during 

 the winter. Nor has it been possible in my breeding experi- 

 ments in Canada and England to carry insects through the winter 

 in the pupal stage. . . . Until evidence is secured of the insect 

 overwintering in the pupal stage, we shall be justified in believ- 

 ing, from the facts available, that in northern latitudes M. 

 domestica is accustomed normally to winter in the adult stage. 

 In more southerly latitudes, where the temperature is much 

 higher, and where the activities of the flies are practically con- 

 tinuous throughout the winter months, one would expect the 

 occurrence of insects in an active condition and of the various 

 stages of development during this period." 



ECOLOGY 



Forbes (38) urges students of economic entomology to study 

 ecology. Denning ecology ' as the relation of organisms to 

 their environment, organic and inorganic, and any and all organ- 

 isms, man included — man, indeed, as by far the most important 

 living factor, from whatever view point," he insists that these 

 relations are three: 1st, interactions (dynamic relations); 2nd, 

 space relations (static relations) ; 3rd, successional relations 

 (genetic relations). The dynamic factor is the only one that 

 interests the economic entomologist; and twentieth century 

 man, as a dominant species, is an important element of that 

 factor. 



Shelf ord (109) reminds us that scarcely any of the pests of 

 forage and garden crops are forest animals and that only a few 

 of the orchard and small fruit pests are strictly so. These pests 

 naturally fall into those that frequent moist places and those 

 that prefer higher and drier ground. The original home of the 

 former was the lowland about streams, lakes and marshes; while 

 the latter originated on the steep lake and river fronts and on 

 exposures of bare rock. Hence, originally our pests were crowded 

 into the cracks of the forest and scattered along the river margins 

 of the great plains. With the clearing of the land and the plant- 

 ing of crops the habitats of these pests were expanded. 



Banks (8) writes: " Since the main orders of insects have 

 existed on the earth the gross outlines of the continents have 



