Dee 15, 1920 



Rice Weevil, (Calandra) Sitophilus oryza 



415 



Table II contains data concerning the preoviposition period, the ovi- 

 position period, and the number of eggs laid. The records of the 10 

 individuals cited were selected as being representative. 



Table II. — Data concerning ovi position and longevity of Sitophilus oryza at 



Orlando, Fla., 191Q 



Weevil No. 



Average. 



Date 



weevil 



emerged. 



July 



14 



18 



Aug. 10 



Date 



first egg 



was 



laid. 



July 



Aug. 19 



26 



Length of 

 preovi- 

 position 

 period. 



Days. 



Date 



last egg 

 was 

 laid. 



Oct. 5 

 24 

 Dec. 7 

 Oct. 3 

 Sept. 19 

 Nov. 7 

 Oct. 22 

 Nov. 5 



¥$? N r ber 



position ° Jf s 

 period. 



Days. 

 89 



108 

 149 

 80 

 67 

 no 



270 

 552 

 576 

 288 

 420 

 445 

 339 

 237 

 389 

 284 



380 



Date of 

 death. 



Oct. 



-'5 



Dec. 



Oct. 5 



Sept. 23 



Nov. 20 



Oct. 23 



Nov. 28 



Dec. 6 



Nov. 26 



Length 

 of life. 



Days. 



95 

 "3 

 179 



93 



78 

 130 



98 

 in 

 119 

 101 



From Table II it will be seen that the average preoviposition period 

 is about 7 days, the average oviposition period during the warm months 

 of the year is 93.9 days, and the average number of eggs laid per female 

 is 380, or about 4 per day. > 



DESCRIPTION OF EGG 



Egg opaque, shining, white, ovoid to pear-shaped in form, widest below middle, 

 bottom broadly rounded, neck narrowing sharply towards top, which is somewhat 

 flat and bears a small protuberance that fits into a cap or plug which cements the 

 egg into place. Length 0.65 to 0.70 mm.; width 0.28 to 0.29 mm. 



INCUBATION PERIOD 



The eggs usually hatch in from 3 to 5 days during the warm months 

 of the year, although by far the majority of them hatch in 4 days. 

 During the colder weather of winter the incubation period is somewhat 

 longer and may last 10 or more days. The variation in the length of 

 the incubation period at different times of the year may be seen in 

 Table III. 



EARVAL PERIOD 



The embryo develops within the egg with its head toward the top, 

 the darker color of the mandibles showing through the thin, transparent 

 shell some time before the egg hatches. The eggshell undulates with 

 the movements of the newly formed larva but is finally ruptured and 

 the young larva begins to feed on the tissues of the corn. 



The egg is usually placed so that at least part of it is embedded within 

 the soft white starch of the grain so that the young larva is at once sup- 

 plied with a readily available food supply. Occasionally the egg is sur- 

 rounded entirely by the horny portion of the seed, and in this case growth 

 of the larva is somewhat slower until it makes its way to the softer 

 white part. 



