135 



Severin (H. H. p.). Summary of Life-history of Beet Leafhopper 



{Eutettix tenclla, Baker). — // Eco)i. Ent., (Jeneva, N.Y., xiv, 

 no. 5, October 1921, pp. 433-436. [Received 13th January 1922.] 



In the present observations it is assumed that the first pale green 

 adults which invade the cultivated area represent the first or spring 

 generation. The eggs hatch in from 11 to 15 days, the shortest period 

 occurring from July to September. The hatching period is greatly 

 influenced by the temperature. Eggs laid from 1st November to 

 15th January either failed to hatch or the nymphs died in the field 

 during the winter. The nymph al periods of the first brood varied 

 from 23 to 37 days, from April to October. Light-coloured adults 

 rarely survive the winter. From the dark females hibernating in the 

 cultivated area four generations were bred. The months of maximum 

 emergence of these four broods correspond to those in which the 

 second to the fifth generations were reared from the pale green leaf- 

 hoppers, viz., June to July, July to August, .September to October, 

 and October to November. The dark leaf-hoppers first appear in 

 the cultivated area in August, and are abundant from September to 

 November. There is a marked decrease in the number of males 

 during December and of females during March and April. The adult 

 Hfe of the dark males is probably about four months, and that of the 

 females about seven or eight months. The dark males follow the 

 females to the plains and foothills and die during the winter. Most 

 of the first-brood pale green males remain behind during the spring 

 on the plains and foothills, and probably die after the pasture vege- 

 tation becomes drv. 



Lathrop (F. H.). Observations on the Biology of Apple Aphids. — 



Jl. Econ. Ent., Geneva, N.Y., xiv, no. 5, October 1921, 

 pp. 436-440. [Received 13th Januaiy 1922.] 



The observations here described on Siphonaphis padi, L. {Aphis 

 avenae, ¥.), Aphis pomi, De G., and A. sorbi, Kalt , were carried out 

 during 1915 and 1916 in Western New York and since 1917 in Western 

 Oregon. 



In Western New York S. padi is the predominant species. A pomi 

 is the next most abundant, its numbers increasing in midsummer. 

 It often causes severe injury to young plantations and the more 

 succulent parts of mature trees. A. sorbi is the least numerous 

 of the three, but owing to the fact that it causes malfomiation of the 

 fruit, it is a serious pest wherever it occurs. It is the most common 

 species in Western Oregon, where S. padi is rare on apple, although 

 it occurs commonly on grains and grasses. S. padi is apparently not 

 a conspicuous pest of apples in regions where, owing to climatic 

 conditions, the winter can be passed on Graminaceae. 



A . pomi occurs in greatest abundance in early summer in Western 

 Oregon, but seldom causes severe injur3^ The hatching period of 

 these Aphids is longer in Western Oregon than in Western New York. 

 In the latter district 5. padi began to hatch on the 22nd April, A . pomi 

 four days later, while A. sorbi was intermediate between the two. 

 In Western Oregon A. pomi hatches from 9 to 15 days later 

 than A. sorbi. It was impossible to determine the exact date of 

 hatching of 5. padi, owing to its scarcity, but it certainly occurs from 

 10 to .15 days earlier than A. sorbi, making an interval of from 19 to 



