28 REPORT ON INJURIOUS INSECTS FOR 1907. 



young trees, photographed in figure 3. The aphids exist in reality in 

 small numbers on all parts of the young apple trees, but do not appear 

 in the photograph except where they exist in colonies. Some weeks 

 after this photograph was taken, the entire trees, stems, roots, and even 

 the petioles and midribs of the leaves were white with woolly-aphis. 

 The insects appeared to thrive as well in the open air as in the soil, and 

 in these cases both the root and limb forms were derived from the same 

 parent. 



But in order to determine whether or not the limb form would 

 spread to and infest the roots, some woolly-aphis from the limb of an 

 infested tree in Jackson county were obtained and introduced, June 28th, 

 on the limbs of the young apple trees in the two other root cages. The 

 trees contained no insects except those placed on the limbs. The root- 

 cages were isolated in large breeding cages in the greenhouse. In the 

 course of a week the aphids had established flourishing colonies on the 

 branches, and at the expiration of a month they had spread down the 

 trunk in scattered and isolated places, and in one case had attacked the 

 roots near the trunk. In two weeks more the roots of all the trees had 

 several well established colonies upon them. 



From these observations and facts it is believed that what little of 

 the aerial or limb form of the apple tree woolly aphis we have in this 

 state is now derived from the root form. Of course it will be understood 

 that I do not imply by this statement that the original form of this aphis 

 was root inhabiting, for I am decidedly of the contrary opinion." 



Apart from the great damage these pests do to fruit trees, by 

 draining the vitality, the wounds formed by their punctures ultimately 

 expose the trees to fungus attacks. Wherever these punctures occur 

 on young wood, there is an abnormal growth of the tissue, which takes 

 the form of rounded or irregular swellings. Later, these gall-like lumps 

 split (and are often stated to be u canker "), and it is in these splittings 

 that fungi and other pests find lodgment. 



PREVENTIVE AND REMEDIAL MEASURES. 



So long as people are allowed to neglect their orchards, or even a 

 few trees, this pest will be with us, and can only be controlled by 

 exercising most drastic treatment. 



In an orchard adjoining the one mentioned above, the following 

 treatment was followed out in 1907, and although only a few yards from 

 trees worse affected than I have ever seen before, it now remains 

 comparatively clean. 



In January the trees were sprayed with the Vi Fluid. In 

 December the soil around the trees was taken away, and without 

 actually touching the roots, Apterite was scattered all around. It is 

 proposed to give all the trees a dressing with the V2 Fluid early in the 

 Spring. 



