RECENT STUDIES OF THE MEXICAN COTTON BOLL WEEVIL. 25 



Although the 1913 records on the oviposition period did not in any 

 case approach the maximum recorded period, the average length 

 was almost 5 days longer than the average of all previously recorded 

 experiments. 



EXTERNAL DEPOSITION OF EGGS. 



In all types of breeding series and at all times during the season 

 females were observed to deposit eggs externally. Usually, when the 

 eggs were deposited externally, the female was either infertile or 

 about through ovipositing but not infrequently fertile eggs were 

 deposited externally by females on the same day they deposited a 

 number normally. A few observations were made of fertile females 

 depositing eggs in empty glass tubes. Every time this happened the 

 female would turn and immediately eat the egg. This habit of 

 eating eggs deposited externally was observed many times and 

 undoubtedly greatly reduced the number found. 



The eggs deposited externally were found in all manner of positions 

 on the calyx and bracts of squares, some even being found on the 

 outside of the bracts. When covered with a moist cloth and placed 

 on damp sand several of the eggs hatched. In one case an egg 

 hatched within 24 hours after deposition and two others hatched 

 within 48 hours. As eggs in squares at this time were taking 3 and 

 4 days to hatch it seems evident that the period for those deposited 

 externally was shortened by the greater exposure to the heat at the 

 time. The tissue of the squares surrounding those deposited nor- 

 mally probably reduces the temperature affecting the eggs. 



A number of larvae were observed after hatching from eggs deposited 

 externally. Although several of these larvae were very near punc- 

 tures in the square not one was observed to make its way into the 

 square. They all moved around considerably but died within about 

 one day after hatching. In one case a larva hatched from an egg 

 placed about half inside a puncture and died without entering the 

 square. 



Some of these larvae were taken immediately after hatching and placed 

 in an incision in a square. These larvae lived and matured. One 

 larva hatched from an egg deposited on the petal of a Hibiscus bloom 

 was placed in an opening in a Hibiscus bud and reached pupation safely. 



Many of the eggs deposited externally were not observed for hatch- 

 ing, so no record can be given on the percentage of these eggs that were 

 infertile, but in one series of females that were depositing fertile eggs 

 all eggs deposited externally were kept and records made on the 

 number hatching. A total of 20 eggs was deposited externally in 

 this series and, of these, 3 hatched, or only 15 per cent. From this 

 and the general observations made during the season it seems evident 

 that by far the greater part of the eggs deposited externally are 

 infertile, but occasionally fertile eggs are deposited in this manner. 



