70 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 9 



daily mean temperature was 50° F. Evidently this temperature 

 does not prevent the development or activities of the parasite. From 

 the dead lice which were collected on January 17, adult parasites 

 emerged sixteen days later, or on Februarj' 2, The average daily 

 mean temperature during this period was 59° F. On the night of 

 February 6, the unusual temperature of 17° F. occurred. Lice which 

 died on February 2 and were exposed to this cold were collected. 

 Fifteen days after the lice died and eleven days after the freeze, 

 parasites emerged from these lice. During this period the average 

 daily mean temperature was 49° F. 



The parasites were present onl}^ in limited numbers during the 

 period from September 1914 to May 1915. During this time the 

 importance of predaceous enemies was strikingly demonstrated. In 

 four widely separated sections of the state the turnip louse was held in 

 check by coccinellids. The presence of the predaceous enemies was 

 much more constant over the state than the presence of the parasites. 



The coccinellids were found to be always present where the turnip 

 lice occurred. Three species were found over the state. They are 

 Hippodamia convergens Guer., Megilla maculata DeG., and Coccinella 

 munda Say. The first two named species were about equally abundant 

 and the last was present only in limited numbers. In some sections of 

 the state the spotted lady-beetle was called the "cold weather" lad}^- 

 beetle. Our observations seemed to bear out the general statement 

 that H. convergens is the more active and abundant in the fall and 

 spring and M. maculata is the more active and abundant during the 

 winter. 



The syrphid flies were widely distributed over the state. At College 

 Station they were quite numerous at times. Syrphus americanus 

 Wied. was found generally distributed over the state. In the southern 

 part of the state the oblique syrphid, Allograpta ohliqua Say, was 

 often found. In the spring of 1915 this species was also taken at 

 College Station. 



The chrysopa fly was usualty found -in all fields where the turnip 

 louse was abundant. 



The fungous disease is a factor of natural control which was very 

 interesting on account of its sudden appearance and its effectiveness 

 in eradicating the turnip louse. The fungus which was observed 

 was undoubtedly Empusa sp., probably Empusa aphidius, though 

 four species of this genus have been reported from Aphids. 



This fungus was first noticed in the fall of 1913 on November 12. 

 At this time many dead lice were found; some were orange in color 

 and soft while others were brown and dry. These lice were mostly 

 pupse, though there were some immature apterous, and a few winged 



