INSECTS INJURIOUS TO CABBAGE, ETC. 337 



regions suffer, but every home garden is damaged by the turnip 

 louse. 



The food plants of the turnip louse are turnips, cabbage, 

 mustard, cauliflower, kale, rutabaga and rape. 



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 26th parallel, 

 to Wichita Falls, on the 34th 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 gen- 

 erations of the lice were reared in pot 

 cages in one year. 



Two other species of plant life are 

 often found closely associated with the 

 turnip louse. These are the "garden 

 aphis " and the cabbage louse. 



The natural factors, of control of the 

 turnip louse are widespread over the 

 State. Two species of parasites, Dia- 

 eretus rapae Curt., and Lysiphlebus 

 testaceipes Cress., have been commonly (After Paddock.) 

 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 Hippodamia convergent Guer., 

 Megilla maculata DeG,, and Coccinella munda Say. Syrphid 

 flies and lace-wing flies are usually found in limited numbers 

 where the turnip lice are abundant. A fungous disease was very 

 destructive to the turnip louse during the season of 1914 at College 

 Station. 



For the artificial control of the turnip louse, spraying is the most 

 satisfactory method. Of the materials which can be used for spray- 

 ing, laundry soap solution gives as satisfactory results as any and is 

 easily obtainable. The secret of success in the control of the turnip 

 louse is the use of the 45 elbow and an " angle " type spray nozzle. 



