1918.] ECONOMIC ZOOLOGY — ENTOMOLOGY. 561 



control the plant lice by spraying infested trees when only the dimorphs are 

 present since they lie so flat on both the upper and lower surfaces of the leaves 

 that it is difiicult to reach any large percentage of them with the spray. The 

 ti-ue sexes appear in October and eggs are deposited on the bark, twigs, and 

 branches of the trees. Observations of 12 generations are recorded, the di- 

 morphs having first appeared in the fourth and in the four succeeding. It is 

 thought that under normal conditions there are six or seven generations in- 

 cluding a generation of dimorphs in midsummer. Technical descriptions are 

 given of the several forms. 



Syrphid flies are its most important natural enemies, two species, Allograpta 

 obliqua and Syrphtis americanus, having been common at Ames in 1912. The 

 larvse of an agromyzid species (Leucopis sp. near griseola) and a cecidorayiid 

 (Aphidoletes sp. ) were observed by the author to feed upon this aphid. Among 

 other predacious enemies observed are several species of lady beetles (Hippo- 

 damia convergens, Cycloneda sanyuina, Adalia bipimctata, and Scymnus ameri- 

 canus), the insidious flower bug {Triphleps insidiosus), a capsid (Plagiogna- 

 thus annulatus), chrysopid larvae (Chrysopa nigricornis, C. plorabunda, and 

 C. oculata), and a large red mite (Rhyncliolophus pilosus). Hymenopterous 

 parasites serve as important checks, Praon coloradensis having been the most 

 common species, and Aphidius polygonaphis was reared. 



Control measures recommended include the use of blackleaf 40 (1 : 500) in the 

 early spring against the eggs on the bark ; and 6§ per cent kerosene emulsion 

 or whale-oil soap (1:10) against the plant lice on the leaves when abundant 

 In May and September. Since only the dimorphs are present during the sum- 

 mer, the spraying must be done before June or after September 1. 



A list of 24 references to the literature is appended. 



Aphis immunity of teosinte-corn hybrids, W. B. Gernert {Science, n. ser., 

 46 [1917), No. 1190, pp. 390-892) .—The data here presented relate to first 

 generation hybrid plants from seed produced by fecundating teosinte (Eticlcena 

 mexicana) with pollen of yellow dent corn {Zea indentata), which species 

 hybridize freely. The author observed that whereas both the roots and foliage 

 of corn plants were heavily infested with aphids, no aphis was ever discovered 

 upon either the teosinte or hybrids nearby. 



Chermesidse in relation to British forestry, H. M. Steven (Trans. Roy. Scot. 

 Arbor. Soc, 31 (1917), pt. 2, pp. 131-155, pis. If, figs. ^).— A summary of infor- 

 mation on this family in which particular attention is given to their life history. 



The fluted scale (Icerya purchasi), E. R. Speyer (Dept. Ayr. Ceylon Leaflet 

 S {1917), pp. 4, fig. 1). — A summary of information on the cottony cushion scale 

 In Ceylon. 



Icerya purchasi in Ceylon: A warning to India, T. B. Fletcher (Agr. 

 Jour. India, 12 (1917). No. 4, pp. 525-531, pi. 1). — The discovery of the cottony 

 cushion scale In Ceylon in December, 1915, an account of which has been noted 

 above, and its rapid spread on Acacia spp. and citrus, together with the possi- 

 bility of Its introduction into India, have led to the preparation of this account. 

 A list of 36 titles to the literature consulted or quoted is included. 



Studies on the morphology and susceptibility of the eggs of Aphis avense, 

 A. pomi, and A. sorbi, A. Peterson {Jour. Econ. Ent., 10 {1917), No. 6, pp. 

 556-560). — This is a report of studies made at the New Jersey Experiment 

 Stations. 



A series of experiments conducted with various insecticides and other chemi- 

 cals, briefly summarized, shows conclusively that the eggs of these three species 

 are susceptible to various Insecticides, particularly lime-sulphur and lime-sulphur 

 combined with nicotin, and that they are also susceptible to various chemicals 

 not generally used as insecticides. Orchard experiments with lime-sulphur 



