May, 1914.] Egg-Laying of the Rice Weevil. 323 



The insects are quite easily disconcerted. They discon- 

 tinue operations and remain still a few moments when disturbed 

 by noise or by the movement of a nearby object, and frequently 

 quit the place entirely. This sensitiveness abates as the cavity 

 deepens, until, during the operation of depositing the egg, the grain 

 on which the weevil is at work may be handled without disturbing 

 the insect. 



The time required in making the cavities varies greatly. Out 

 of six operations of which the time was taken, the shortest was 

 thirty two minutes, while the longest period observed was one 

 hour and forty five minutes, and this time was spent in completing 

 a cavity which was apparently one-half finished when observation 

 began. 



DEPOSITING THE EGG. 



When the cavity is finished, the proboscis is slowly and hesitat- 

 ingly withdrawn. The weevil then turns around over the opening, 

 and walks slowly forward a few steps, at the same time swinging 

 the abdomen from side to side, thus searching for the mouth of 

 the cavity. When the tip of the abdomen comes in contact with 

 the opening, the weevil stops, and places the ovipositor in posi- 

 tion. During egg-laying, the ovipositor may be observed some- 

 what distended by the passage of the egg. There is a slight move- 

 ment of the tip of the abdomen, probably aiding in forcing the 

 egg into the cavity. 



In one instance it was observed that a weevil, when the cavity 

 was finished, turned al^out as usual, but failed to find the opening 

 with the ovipositor. The insect then moved backward until the 

 proboscis was over the cavity, facing in the opposite direction 

 from that when the cavity was dug. After a little additional 

 digging, the weevil successfully inserted the ovipositor, and depos- 

 ited the egg. 



The time consumed in depositing the egg varies from three to 

 seven minutes, the average being 4.3 minutes. The average num- 

 ber of eggs laid per day by a single weevil was found to be 1.2. 

 This was determined from records including twenty weevils 

 laying a total of 378 eggs. The largest number of eggs deposited 

 by a weevil in one day was 9, while 03 eggs in 46 days was the 

 greatest total number of eggs deposited by one weevil. This does 

 not represent the total number of eggs laid during the life of the 

 insect. The rate of oviposition as well as the total number of 

 eggs deposited varies with the conditions under which the eggs 

 are laid. Probably the most important factors are the degree 

 of hardness of the corn and the temperature and moisture condi- 

 tions. Hinds and Turner (3) found that a single weevil is capable 

 of laying as many as 417 eggs during a period of 110 days. 



