512 



plants, such as evening primrose, hedge nettle, sow thistle, wild 

 geranium, vetch, blackberry, and Jerusalem oak. The first spring 

 generation of females develops about 31st March, Between this date 

 and the end of May about five broods occur and migration to other 

 weeds, garden plants, and cotton takes place. In the latitude of South 

 Carolina the spring and summer generations mature in less than 11 

 days, while during an average season 17 generations are produced. 

 The incubation period of the eggs of both sexes is about four days, 

 tliough males reach maturity slightly sooner than the females. Mature 

 fem.ales on cotton feed for about 18 hours before ovipositing. Eggs 

 are deposited in clusters on the under surface of the leaves, each female 

 laying about six eggs daily during a period of from 8 to 10 days. 

 Feeding continues at intervals during the egg-laying period. The 

 duration of the adult stage in summer is about 12 days ; this period 

 increases with a fall in temperature and in winter may extend over 

 150 days. Migration to winter hosts takes place in late autumn. 

 In addition to the wild plants above mentioned, cultivated violets 

 frequently become infested. Adult females are able to travel over 

 smooth surfaces at the rate of 600 feet in 24 hours. Dispersal is 

 effected by active migration, heavy rains, and by wind. 



Predaceous enemies include mites, thrips, bugs, lacewing flies, 

 S5?rphid flies, midges, etc. Preventive measures include (1) the des- 

 truction of weeds in or near cotton fields ; (2) control on cultivated 

 plants by spraying with sodium arsenate at the rate ofllb. to20U.S. 

 gals, water ; (3) crop rotation with wild grasses and small grains ; 

 (4) the maintenance of a finely- pulverised surface mulch to hinder as 

 far as possible migration from one plant to another ; (5) the use of 

 fertilisers to promote vigorous growth of the cotton plants. When 

 infestation first appears in cotton fields, affected plants should be 

 removed and destroyed. In cases of more general infestation, appli- 

 cation of one of the following sprays is recommended : — (1) Potassium 

 sulphide, 1 oz. to 2 gals, water ; (2) lime-sulphur ; (3) kerosene 

 emulsion ; (4) flour-paste solution, 1 gal. stock solution to 12 ga]s. 

 water. The spray should be applied very thoroughly and should be 

 repeated a week later. 



Gibson (E. H.). The Clover Leafhopper and its Control in the Central 

 States. — U.S. Dept. Agric, WasJmigton, B.C., Farmers' Bull, 

 no. 737, 26th June 1916, 8 pp., 5 figs. [Received 3rd October 

 1916.] 



Agallia sanguinolenta, Prov., occurs in southern Canada, throughout 

 the United States, and in Mexico. The principal host plants include 

 certain leguminous crops, such as lucerne, clover, cowpea and vetch. 

 This Jassid is also common on native and cultivated grasses, and has 

 been found on wheat and sugar-beet. The most serious injury to 

 clover and lucerne in the central States is caused in the spring and 

 early summer, when the epidermis of the stem and leaf is thin and 

 easily punctured. Seed production may be affected by the puncturing 

 of the flower buds and petals, while distortion or gall-formation may 

 result from the deposition of eggs in the stem or leaf tissue. The 

 incubation period of the eggs during the summer in southern Illinois 

 varies from 5 to 12 days and the nymphal stage from 18 to 35 days. 



