4 Control of the Greenhouse White Flij 



eggs on foliage severed from the plant shrivel and die. Even were this 

 not the case the larva has not that power of movement enabling it to 

 pass on to living plants. 



In Al. citri the wintering stage is the pupa (2) and the phenomenon 

 of partial brooding, such as is familiar in the case of many Lepidoptera, 

 occurs, some of the pupae going into the wintering condition quite early 

 in the season and the proportion which so delay emergence increasing 

 as the cold weather approaches. No such partial brooding occurs in 

 Ast. vaforariorum and its dependence on living foliage shows that it is 

 not fully adapted to a temperate climate where the occasional occurrence 

 of severe winters, when all foliage except that of leathery evergreens is 

 cut d©wn, must exterminate it out of doors. 



Table I. Showing shade temperatures {degrees F.) in greenhouse 

 and outside during investigation. 



3. FOOD PLANTS. 



The insect has a wide range of food plants but those which suit it 

 best have rather thick sappy leaves and among its most favoured hosts 

 may be mentioned the following: tomato, potato, cucumber, vegetable 

 marrow, French beans, tobacco, hollyhock, calceolaria, dahlia, helio- 

 trope, stinging nettle. On these plants practically every egg laid produces 

 an adult under favourable circumstances. On a number of hard leaved 

 plants it can breed successfully but the mortality of the larvae is great 

 and the plants do not frequently become massively infested. Such 

 plants are the grape vine, various fuchsias, Calla, begonias, geraniums. 



