1917 EXTOMOLOUICAL SOCIETY. 43 



the time_w]icn the apples are about the size of a good marble (about half an inch 

 in diameter), or from about the middle of August to the time of picking. The first 

 period 1 have mentioned you will find will be the one for about five seasons out of 

 six. I have never sprayed more than three times. If you have your orchard per- 

 fectly clean for the first period, it takes a long time for the scab fungus to become 

 abundant again that year. 



Mr. Deakxess : In regard to the scattering of the summer spores, do you find 

 this to be about the first of July? This fungus has its first period of infection, of 

 course, directly from the over-wintering spores. 



Pkof. Caesar: I may say in regard to the times of infection that the first 

 infection comes on the leaves nearly .always, and it comes from the ascospores on 

 the leaves on the ground. As soon as those develop to fructification — which is in 

 about two weeks usually — you have then what you call the summer spores. You 

 can never be sure of the date; it depends upon the weather conditions. 



Mr. Biggar: Has the dormant spray anything to do with the control of 

 Scab? 



Prof. Caesar: Some seasons it has, and I think probably in 'our case it 

 had because we gave a ver}^ heavy application for San Jose Scale, and everything 

 on the irround was drenched. 



, GENERAL NOTES ON APHIDES WHICH OCCUR ON APPLE TREES. 



William A. Ross, Yixeland Station. 



The purpose of this paper is to present brief notes on ten species of aphides 

 which have been taken on the apple in Ontario. Four of the insects, viz., Aphis 

 pom I, Aphis mnlifolicp. Aphis avence and Eriosoma lanigera, are noxious; the 

 others, viz: Apliis hal-eri, Aphis hrevis, Aphis sp. (near gossijirii), Macrosiphum 

 salanifolii, Mijzv.s pcrsica' and Macrosiphum pelargonii (?) are, so far as our 

 observations have gone, of little or no economic importance. 



The Green Apple Aphis {Aphis pomi De Geer). This species is the most 

 troublesome plant-louse with which Ontario orchardists and nurserymen have to 

 contend. It attacks, curls and sometimes kills the foliage, and_ in cases of severe 

 infestation, it may even feed on the fruit. It has a very pronounced predilection 

 for succulent shoots and water sprouts, and in fact, if not provided with these ' 

 delicacies, it will not thrive and multiply rapidly. The aphis produces a generous 

 supply of honey-dew, and because of this it is well patronized by ants. The l)lack 

 fungus which develops in this honey-dew gives the foliage, twigs and sometimes the 

 fruit of an infested tree a sooty and very unsightly appearance. 



The eggs of Aphis pomi hatch in April when the buds of apple trees are 

 swelling and commencing to burst. The stem-mothers, i.e., the aphides which 

 hatch from the eggs, reach maturity, and commence reproducing in somewhat less 

 than three weeks. During the next month or so each female which survives all the 

 perils to which plant-lice are suhjoct, cfivcs l)irth on an average to 70 young (74 

 was the average obtained from IS individuals in our 1015 experiments). The pro- 

 geny of the stem -mothers for the most part develop in from two to three weeks into 

 apterous viviparre. A number of this generation, however, and a still larger 

 number of the third generation become alate and migrate to other apple trees. 

 The third generation is succeeded by brood after brood of wingless and winged 

 vivipara^ until by the close of the season as many as fourteen or fiftoon gcTicrations 



