imol ECONOMIC ZOOLOGY — ENTOMOLOGY, 849 



stroy a plant. In considering its biology the author compnres that of the 

 potato leaf-hopper with Tijphlocyba rosw and E. imieolor. 



Its natural enemies include an undetermined dryinid which parasitizes the 

 egg, and a fungus {EntoniopMliora sphcrosperma) which desti'oys large 

 numbers. As regards control measures the author recommends the applica- 

 tion of blackleaf 40 at the rate of 1 part to 800 parts of water to which 5 parts 

 of soap have been added. Since the nymphs feed entirely on the under surface 

 of the leaves the spray nozzles should be set to direct the stream upward. Tlie 

 applications sliould be made as soon as the first burning appears on the leaves, 

 that is, late in June or early in Jitly. Arsenicals for the control of the Colorado 

 potato beetle may be added to tlie mixture, or the whole, omitting the soap, 

 may be added to Bordeaux. Where kerosene emulsion Is iTsed it should be as 

 strong as safety to the foliage permits, 7 or 8 per cent of kerosene or 1 part 

 of the stock emulsion in 8 parts of water having been found satisfactory. 



An illustration is given of a drag board attachment which bends the plants, 

 thus exposing the under surface of the leaves to the spray. A bibliography of 

 39 titles is appended. 



The potato leaf hopper and its relation to the hopperburn, E. D. Ball 

 (Jovr. Econ. Ent., 12 (1919), No. 2, pp. lJf9-155, pi. 1, fig. i).— A more detailed 

 account is given in the paper above noted. 



Report of a second collection of Nova Scotian eupterygid leaf hoppers, 

 including' descriptions of new varieties, ^V. L. I^IcAtee {Canad. Ent., 51 {1919), 

 No. 10, pp. 225, 226). 



A study of the plant lice injuring the foliage and fruit of the apple, R. 

 Matheson {New York Cornell Sta. Mem. 2Jt {1919), pp. 683-762, pis. 23, figs. 

 10). — This is a report of studies at Ithaca, N. Y., of the life history and 

 bionomics of the three species of plant lice that are frequently very injurious 

 to the foliage and fruit of the apple, namely, the apple aphis {Aphis pomi), 

 referred to by the author as the green apple aphis (pp. 686-718) ; the rosy ap- 

 ple aphis (A. sorhi) (pp. 718-750); and the European grain aphis {[Sipho- 

 co)-yne] Aphis avence) referred to as the grain, oat, or apple-bud aphis {A. 

 avenw) (pp. 750-758). 



The apple aphis is the most common and widespread of the three, doing con- 

 siderable injury every year, not only in bearing orchards but also in young 

 orchards recently set and in nurseries. The greater amount of injury caused 

 by this species is due to its remaining on the apple tree throughout the season, 

 whereas the rosy apple aphis and the European grain aphis migrate in May, 

 June, and early July to other host plants. In recent years the rosy apple 

 aphis has also become very injurious and now does as much if not more damage 

 in bearing orchards than does the apple aphis. The author concludes that all 

 three species, now common on apple in all parts of the United States and 

 Canada, are of European origin, having reached the United States in the first 

 lialf of the nineteenth century. The failure to distinguish between the three 

 species has led to much confusion in the literature even to the present day 

 and this, as is pointed out by the author, is all the more noticeable since the 

 three species differ so markedly in their life histories and the character of 

 their injury to the foliage. 



A somewhat detailed account of A. pomi was given in his memoirs by 

 DeGeer who did not confuse it with the other two, but this account appears to 

 have been overlooked until very recent years. The species was first clearly 

 distinguished in this country by Pergande in 1904 (E. S. R., 16, p. 71), and a 

 concise account of its life history was first presented by Smith in 1900 (E. S. R., 

 12, p. 268) under the name A. mali. Important accounts of its biology have 

 been published by Brittaiu (E. S. R., 35, p. 853) and by Baker and Turner 



