Dec. 15 1920 



Rice Weevil, (Calandra) Sitophilus oryza 



413 



As the weevils get older the oviposition rate gradually decreases until, a 

 few weeks before death, egg laying ceases altogether. With the approach 

 of cold weather the rate of oviposition also decreases, and especially is 

 this true of the older weevils. The younger female weevils are more 

 vigorous and are much less affected by the cold. 



Normally eggs are laid every day during the spring, summer, and fall 

 months, but during the winter egg laying is sporadic and is controlled 

 chiefly by the daily temperatures. 



In Florida the winter temperatures are very variable, short periods of 

 cold weather occur frequently, and during these oviposition usually 

 ceases. 



During the warmer months the weevils normally lay from three to six 

 eggs per day in hard corn. 



Table I shows the rate of oviposition at various times of the year. 

 It contains abstracts from the oviposition records of 14 weevils that are 

 representative of the species. The number of eggs laid by each weevil 

 on two consecutive days in each week from June, 1919, to March, 1920, 

 is given, together with the daily mean temperatures and the dates of 

 emergence and death of each individual weevil. The corn was at its 

 most favorable stage for oviposition during the latter part of June and 

 the early part of July. 



Table I. — Rale of opposition of Sitophilus oryza; extracts from oviposition records 

 at Orlando, Fla., June, IQIQ, to March, IQ20 



'Weevil emerged July 5, 1919. 



1 Beetle escaped. 



> Weevil emerged. Aug. 10, 1919. 



d Weevil emerged Aug. 18, 1919. 

 « Weevil emerged Sept. 18, 1919- 

 / Weevil emerged Sept. 19, 1919. 



