60 



do so, she plainly objected to placing an egg in that particular square. 

 The writer again examined the square carefully, but found no sign of 

 infestation and replaced it in the observation cage. Again the female 

 made her usual careful examination and still she plainly refused to 

 oviposit. Upon removing the covering from the square it was found 

 to contain an egg, but the puncture made in depositing it had healed 

 so smoothly that it had thrice escaped observation. The same female 

 was then given two squares, one of which was known to be infested, 

 the latter being placed nearer her. She examined it carefully, then 

 left it, and went at once to the clean square, in which, after the usual 

 examination, she deposited an egg. 



The acuteness and accuracy of the preliminary examination is also 

 well shown by the fact that when provided with more squares than 

 they have eggs to deposit they rarely place more than one egg in a 

 square. It was frequentty found, however, that when a female depos- 

 ited just as many eggs as there were squares present she would place 

 two eggs in one and then make only feeding punctures in the remain- 

 ing square. 



The observations were made upon a large number of females; so 

 there can be no doubt that the habit of selection is general. The 

 conditions provided in these experiments were intended to resemble 

 those existing in a slightly infested field early in the season, where each 

 female could easily find an abundance of clean squares in which to 

 deposit her eggs. Therefore only those cases were recorded in which 

 the number of squares present equaled or exceeded the number of 

 eggs deposited. Where a totally infested condition is reached no 

 choice between infested and uninfested squares could be exercised, 

 and then unless the female happened to be in a condition to refrain 

 from oviposition she would be forced to deposit more than one egg 

 in a square. 



Not only do females show a strong inclination to place only one egg 

 in each square, but they also object to making both egg and feeding 

 punctures in the same square. That these conclusions are well 

 grounded may best be shown by giving a summary of two long series 

 of observations, the first made in the laboratory in the fall of 1902 

 and the other made in the field partly in the fall of 1902 and partly in 

 the spring of 1903. 



LABORATORY OBSERVATIONS. 



Nine females were used in this series of experiments. The time 

 followed varied with each individual, but ranged from October 23 to 

 December 18, 1902. During this period a total of 868 uninfested 

 squares was supplied to these 9 females. Of these squares 238 were 

 not touched, while 630 were punctured, either for oviposition or for 

 feeding or for both. The general results are here summarized in 

 tabular form. 



