32 ASSOCIATION OF ECONOMIC ENTOMOLOGISTS. 



pieces of glass were held in position with Canada balsam, and a 

 cover glass was placed on top to prevent the escape of the insect. All 

 observations of birth in this ceil were made under a microscope, using 

 a two-thirds or one- fourth inch objective. 



The manner of birth, as repeatedly observed by me, is as follows : 

 First there is a contorted movement of the abdomen of the mother, 

 which is immediately followed b} T the appearance of the young 

 aphis as an egg-like object at the anal opening. In about thirty 

 seconds the body of the young is forced out until the eyes appear, 

 when the movement is checked, then ceases entirely, with the mother 

 retaining a hold on the crown of the head. At this time the dark 

 spots that mark the eyes are the only means by which the object 

 might at first be distinguished from an egg. The antennae, together 

 with the legs, are bent toward the tip of the abdomen and held closely 

 against the ventral surface by a transparent membranous sac. This 

 sac soon breaks at the crown of the head and is worked backward 

 (cauclad) by a continuous expansion and contraction of the body, 

 accompanied by an interrupted pulling and pushing movement of 

 the antenna 1 and legs. These motions are similar to those of an insect 

 working its way out of a pupa case. The progress of the membrane 

 as it moves backward (caudad) is at first indicated only by the hairs 

 at the base of the antennae and on the head springing into an erect 

 position as they are freed. In from three to five minutes after the 

 membrane begins moving off, the antennas are liberated, and a small 

 amount of whitish substance appears at the tip of the abdomen. 

 Each pair of legs is then liberated in turn. As the sac works farther 

 back its ragged edge becomes visible and the shriveled membrane at 

 the tip of the abdomen increases in quantity. The last pair of tegs 

 is freed in from three to seven minutes after birth. As soon as the 

 legs are freed they begin to kick vigorously, the kicking continuing 

 from one to two minutes after the last pair is liberated ; whereupon 

 the mother lowers her abdomen and presses her offspring down, seem- 

 ingly with the intention of assisting it in getting a firm footing, and 

 at once loosens her hold. After the young is on its feet, the cast 

 pellicle adheres to the tip of the abdomen for about two minutes, 

 when it is worked off, leaving the insect smooth and glistening, but 

 not yet entirely free, for a waxy thread still connects the seta 1 of the 

 beak with the discarded pellicle. After several tugs and pulls the 

 thread is broken and the insect crawls away. 



Many times I have loosened the young insect from its mother, 

 while she was holding it by the crown of its head, and carefully 

 watched its subsequent movements. Only a slight touch with a 

 camel's hair brush is necessary to break this hold. The motions of 

 the body of the young and the freeing of antennae and legs were iden- 



