PARTHENOGENESIS. 365 



male moths, gnaw open the abdomen, and, after removing 

 the egg-mass, drag it to their nests. With the discovery 

 of these facts the question naturally arose, whether the 

 eggs thus removed from fertilized females would hatch and 

 thus start new colonies in the places to which they had been 

 carried. To settle this point, during the summer of 1895, 

 studies were made on fifty female moths. Some of these 

 moths were taken when the egg-cluster was about one-third 

 completed, some when the egg-cluster was one-half com- 

 pleted, some when two-thirds, and others which had very 

 nearly completed laying. These moths were dissected, and 

 all of the eggs still remaining in the abdomen removed and 

 preserved in boxes. Examinations of these eggs, made 

 subsequently, showed that none of them were fertile. 



A part of the egg-cluster deposited by twenty-five of 

 these moths was preserved, all of which proved more or 

 less fertile. This seems to demonstrate that, notwithstand- 

 ing the mating of the moth, the eggs are not fertilized till 

 during the process of laying. 



PARTHENOGENESIS . 



Parthenogenesis, or reproduction by means of the eggs of 

 unfertilized females, was thought to offer an explanation for 

 the existence of certain peculiarly situated colonies in the 

 infested territory. As has been previously stated, cater- 

 pillars are sometimes dropped uninjured by the birds when 

 they are carrying them away to feed their young ; or they 

 may spin down from the trees upon passing teams or ani- 

 mals, and be carried to greater or less distances and then 

 escape to suitable food plants, where they can feed and 

 pass their transformations. If a single caterpillar should be 

 carried, in any such way, to a distance from any colony 

 greater than males could be attracted, and from it should 

 emerge a female moth, she would doubtless lay her eggs, 

 and, if parthenogenesis occurs in this moth, these eggs 

 might hatch, even though no male had been present to mate 

 with her. 



To ascertain whether eggs laid by unfertilized females 

 will hatch, in July and August, 1893, 990 female pupae were 

 put in small pasteboard boxes and kept under a variety of 



