452 EXPERIMENT STATION RECORD. 



6 per cent strength, during the winter or early spring. Fumigation has been 

 demonstrated to be a positive control measure. Since neither fruit nor trees 

 are shipped from Marysville there seems to be little danger of the pest spread- 

 ing to other sections. 



The life history and habits of the greenhouse white fly (Aleyrodes 

 vaporariorum), E. Hakgeea\-es (Ann. Appl. Biol., 1 {1915), Xo. 3-4, pp. 303- 

 334, fi'js. 56). — A report of anatomical and biological studies of this pest, an 

 extended study of which by Morrill has been previously noted (E. S. R., 15, p. 

 382). 



The occurrence of fungi on Aleyrodes vaporariorum in Britain, A. S. Hobne 

 {Ann. Appl. Biol., 2 (1915), Xo. 1, pp. 109-111).— This article relates to the 

 association of Cephalosporium Icfroyi with the greenhouse white fly. 



Notes on an apparent relation between aphids and fire blight (Bacillus 

 amylovorus), J. H. Merkill (Jour. Econ. Ent.. S (1915), Xo. 4- PP- -'lOi. 403). — 

 The data presented indicate that there is a direct relation between the severity 

 of the infestation of aphidids and blight infection. 



The turnip louse, F. B. Paddock (Texas Sta. Bui. 180 (1915), pp. 7-77, pis. 

 5, figs. 10). — Investigations commenced in the early fall of 1913 led to the dis- 

 covery that the plant louse which has caused much of the widespread injury to 

 turnips and related plants is not the cabbage aphis as supposed, but a distinct 

 species, which has been described by Davis (E. S. R., 31, p. 754) as Aphis pseudo- 

 hrassiccp, and which the author has termeil the turnip louse. 



Tlie investigations have shown the turnip louse to be a serious pest in the 

 winter truck regions of the State and to be generally distributed over the United 

 States, especially where the cabbage aphis is found. It feeils upon many of the 

 same plants, especially cultivated species, and for the most part on the undersur- 

 face of the tender leaves of the host plants, which include the turnip, radish, 

 cabbage, mustard, cauliflower, kale, ruta-baga, lettuce, bean, rape, kohlrabi, 

 and coUard. 



Life history studies with descriptions of forms are reported in detail, much 

 of the data being presented in tabular form. 



" The normal form of reproduction of the turnip louse in Texas is asexual 

 throughout the year. Observations have been made upon this louse in Texas 

 from Brownsville, on the twenty-sixth parallel, to Wichita Falls, on the thirty- 

 fourth parallel. True hibernation does not take place in Texas; even at the 

 northernmost point of occurrence the lice reproduce some during the winter. 

 The summer is the critical period in the life history of the turnip louse, as it is 

 forced to sheltered locations and none of the cultivated host plants are grown 

 at that time of the year. Thirty-five generations of the lice were reared in pot 

 cages in one year. Two other species of plant lice are often found closely asso- 

 ciated with the turnip louse. These are the ' garden aphis ' and the cabbage 

 aphis. 



" The natural factors of control of the turnip louse are widespread over the 

 State. Two species of parasites, Diaretus rapw and Lysiphlcbus testaccipes. 

 have been commonly found, the former at College Station and the latter in 

 other sections. Three species of lady beetles have been observed to feed freely 

 on the turnip louse. These are Ilippodamia convcrgens, Mcgilla maculata, and 

 Corcinflla imnida. Syrphid flies and lace-wing flies are usually found in limited 

 numbers where the turnip lice are abundant. A fungus disease was very de- 

 structive to the turnip louse during the season of 1914 at College Station. 



" For the artificial control of the turnip louse, spraying is the most satisfac- 

 tory method. Of the materials which can be used for spraying, laundry .soap 

 solution gives as satisfactory results as any and is easily obtainable. The 



