SUMMER MEETING. 21 



of the large red apple" it at once becomes apparent that if one can 

 control this pest, it will result in the saving of many thousand dollars 

 each year to this State which now ranks third in the Union in its hor- 

 ticultural interests, of which the apple crop is its most prominent 

 feature. 



Heretofore in this State there seems to have been little attention 

 given to methods of combating this insect, and few people have at- 

 tempted to rid their orchards of this pest or to control and prevent its 

 spread. It appears to be, however, comparatively easy to hold it in 

 check and to be quite readily exterminated in a given area, as has been 

 proven by the experiments herein described. ( See under Remedies.) 



In the northern and eastern portions of the United States and 

 especially in Europe the form that infests the branches of the apple 

 trees is the one that usually does th^ most injury, while in Missouri 

 the form infesting the roots is the only one that does any injury what- 

 ever, the other being only occasionally seen, and when found, occurs 

 only in small, unimportant, and isolated colonies. 



INJURY, HABITS AND LIFE HISTORY. 



The wooly-aphis of the apple, ScJiizoneura lanigera, ( Hausm), is 

 found in nature in two so called forms. One infests the limbs and 

 twigs, while the other lives under the ground npon the roots. Ento- 

 mologists designate the aerial form "wooly-louse of the apple," and 

 the subterranean form "apple-root plant-louse." Some entomologists 

 have described these two forms as distinct species, but at present all 

 appear to be agreed that these two forms are the same species, differ- 

 ing only in habits. The laboratory experiments conducted at this Sta- 

 tion with this insect go to show that the root inhabiting form will, under 

 certain conditions, establish colonies upon the branches or limbs and 

 there thrive in a perfectly natural manner, and vice versa. 



The presence of the aerial form of the wooly-aphis is readily de- 

 tected by the bluish-white cottony or downy looking substance that is 

 excreted by and covers the greater part of each wingless individual 

 aphis; and since these insects live in clusters or colonies, the patches 

 of white matter are very conspicuous, and can scarcely escape the 

 notice cf even the most casual observer. It has been my experience 

 to find in nature this aerial form in Missouri only in rare cases, and 

 then only in those places where some injury had caused an abrasion 

 of the bark, or some limb or twig had been cut or broken off, or where 

 they had been crowded from the ground up to the base of the trunk or 

 on the suckers that had been allowed to grow around the tree. They 

 are frequently artificially induced to attack the trunk by mulching, or 



