MAINE AGRICUIvTURAL EXPERIMENT STATION IQII 289 



cut-leaved maple as well as the native variety of the same 

 species is in Maine dependent for its infestation on the fall 

 migrants from the alder, treasured ornamental maples could be 

 protected by destroying the alder in the vicinity. The practi- 

 bility of this course would depend on the quantity of the 

 neighboring alders. Where this could not be done the land- 

 scape gardener would save himself trouble if he withheld 

 susceptible maples from the vicinity of native alders. 



Considerable detailed study has been given a large green 

 plant-louse commonly abundant upon the potato in Maine and 

 a similar species very destructive to the pea. The distinctive 

 structural characters have been carefully worked out so that 

 these two species can be distinguished in all their forms regard- 

 less of the plant on which they feed. Certain important addi- 

 tions have been made to the list of native food plants which 

 have a bearing on the economic status of these insects. 



So little attention has been previously paid the psyllids or 

 "jumping plant lice" in New England that the station entomol- 

 ogists have felt the need of working with certain species 

 present in Maine. Among those of economic importance might 

 be mentioned an amber yellow and green species injurious to 

 birch leaves in spring, a dark winged species present on shade 

 bushes, a conspicuously marked species on blackberry and a 

 pear tree psyllid which renders the leaves discolored and sticky. 

 These insects are a little larger than plant lice, which they 

 resemble in their feeding habits as they pierce the tissue in 

 the same way and suck their juices. Like plant lice, too, the 

 psyllids secrete a sweet sticky fluid which daubs the surface of 

 the leaves. 



Of the habits and early stages of many species of flies little 

 or nothing is known. This order of insects which was until 

 recently nearly ignored by economic entomologists has of late 

 sprung into prominence -by reason of the direct relationship 

 which some of the species, notably flies and mosquitoes, bear to 

 diseases of man. Other species, the apple maggot, the beet leaf 

 miner, the bean and the seed com maggot among them, are 

 serious crop pests. This has led the station entomologists to 

 devote some time to the investigation of the early stages of 

 these insects. Among them are the fungus gnats, whose 



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