{February-, '16] HAYES: maize bill-bug 125 



independent burrows in the same plant, a condition often found in 

 badly infested fields. Adults, pup», and larvse may frequently be 

 found in a single stalk. 



After becoming established in a stalk of any size, they were never 

 observed to burrow through the tough, outer covering of the plant 

 above ground, but may do so occasionally beneath the surface. 



The length of the larval stage varies considerably. In 1914, on 

 corn, it ranged from 40 to 60 days with an average of 52.5 days. The 

 following table shows the length of the larval stage in 1915 on different 



food plants : 



Length of Larval Stage 



Food No. Attempted No. Max. Min. Aver, 



to rear Matured Days Days Days 



Maize 337 141 69 32 42.83 



Kafir 47 6 68 32 47 .50 



Cane 46 12 75 39 54.83 



Feterita 34 7 52 38 44 .42 



Sweet Corn 13 3 56 43 48.00 



In 1915, the average length of the larval stage, on maize, was re- 

 duced from 52.5 to 42.83 days, almost ten days in a much cooler season. 

 The minimum was also lowered from 40 to 32 and the maximum raised 

 from 60 to 69 days. These results were obtained in an outdoor in- 

 sectary and checked closely with field observations. One larva, feed- 

 ing on cane, was kept alive 123 days, but died before pupation. 



Although larvse were found at work in the fields as early as June 6 

 in 1914, they were not found until July 1 in 1915 and were present 

 thereafter throughout July, August, and part of September. 



Pupa 



Pupation occurs in the pupal cells constructed in, or near, the tap- 

 root of the infested plant. Pupse are generally found in the upright 

 position which the larvse assume just before transformation. At 

 first, they are creamy-white, but in from 4 to 6 days they begin to 

 gradually darken until they are nearly the color of new adults. 



The pupal, like the egg and larval stages, varied considerably in the 

 two seasons under observation. 



Length of Pupal Stage 



Year No. to Max. Min. Aver. Remarks 



Pupate Days Days Days 



1914 11 13 10 11.4 Dry season 



1915 114 30 9 13 .84 Wet season 



Seasonal History 

 There is but one generation annually. Adults that have lived 

 through the winter will sometimes be abroad after their progeny are 

 matured. 



