200 EXPERIMENTAL FARMS. 



be studied critically and their life histories worked out, so that the most suitable reme- 

 dies for those which injure crops may be made known and applied at the proper time. 

 As a contribution towards this knowledge, I am pleased to be able to present herewith 

 careful enlarged drawings of the Apple Aphis (A. mali) and of the joints 3, 4, 5, 6 and 

 7 of its antenna (Fig. 10), made by my esteemed correspondent, Prof. H. T. Williams, 

 of the South Dakota Agricultural College, who has made a special study of the Aphididae. 

 This, I believe, will be of great assistance to British Columbian fruit-growers in iden- 

 tifying the species. 



It is not only in its attack on the apple tree that the Apple aphis levies toll from 

 the farmer, for it is now known to be a serious enemy of fall wheat. 



Prof. Riley in his report, as United States Entomologist for 1889 (p. 351), when treat- 

 ing of the Grain Aphis, says : " Observations are complicated by the fact that several 

 other species of plant-lice are found in greater or less numbers upon wheat. The com- 

 mon Apple plant-louse {Aphis mali, L.) is often found on wheat after the appearance of 

 the winged generation upon apple, and, indeed it is a question whether this species, in 

 view of what we know of its summer migration, should really be known as the Apple 

 plant-louse, any more than the Hop plant-louse should be called the Plum plant-louse. " 



Again Prof. F. M. Webster, of Ohio, in a paper on the " Insect Foes of American 

 Cereal grains {Insect Life, vol. VI., p. 152), writes : — 



" It would appear almost visionary to advocate spraying apple orchards in mid- 

 winter to protect the wheat crop ; but nevertheless one of the most serious enemies of 

 young fall wheat passes its egg stage on the twigs of the apple during the winter season. 

 I refer to the Apple leaf-louse {A. mali, Fab.). Soon after the young wheat plants ap- 

 pear in the fall, the winged viviparous females of this species flock to the fields and, on 

 these, give birth to their young, which at once make their way to the roots, where they 

 continue reproduction, sapping the life from the young plants. On very fertile soils, this 

 extraction of the sap from the roots has no very serious effect; but, where the soil is not 

 rich, and especially if the weather is dry, this constant drain of vitality soon begins to 

 tell on the plants. Though they are seldom killed outright, these infested plants cease 

 to grow, and later take on a sickly look, and not until the aphis abandons them in 

 autumn to return to the apple, do they show any amount of vigour." 



In my last report, I referred to the complaints from British Columbia that many 

 trees had been killed by the Apple Aphis. Commenting on this, Mr. E. Hutcherson, of 

 Ladners, B.C., a good observer, and moreover one who knows well most of the injurious 

 insects of his province, writes as follows: — "I compared aphids I sent you (true 

 Siphonophora avenai. — J. F.) with those on apple and found them different. As regards the 

 Apple aphis killing trees in this province, I do not know, I am sure, where you got your 

 information ; but I have failed to find a case in my experience, and I can assure you 

 that it is not actually the case ; they may have assisted the Bark blight and Woolly 

 Aphis to some extent, as I have found that weak, poor growing varieties and those 

 suffering from other diseases, are the trees most affected. My experience, in my own 

 orchard, has been that a tree affected this year is almost sure to be free the following 

 season. I cannot say that we have been troubled much with the Apple Aphis for the 

 last two years. We have had rains and wet weather in the spring and early summer, 

 and again early in September ; for this reason, the aphids have not been so plentiful as 

 formerly. In this matter I speak not only for my own district, but for the whole pro- 

 vince, up to the end of 1893." 



And in another letter Mr. Hutcherson reverts to the same subject : — " In speaking 

 of the trees being killed by the Apple Aphis in the Okanagan country, I would say that 

 in some of the orchards there I found trees badly affected with Scurfy Bark-louse, which 

 with the aid of the green aphis had killed quite a few trees." With regard to the 

 correct identification of the Scurfy Bark-louse in the above quotation, I have some 

 doubts ; but when I wrote for specimens to the owner of the orchard, I found that the 

 trees had all been cut down and destroyed. 



Remedy. — The most satisfactory remedy for the Apple Aphis I have found to be the 

 Kerosene emulsion, which should be sprayed on the trees early in spring, just as the 



