VIII, B, 1 Mitzmain: Stomoxys calcitrans Linnseus 37 



there follows a splitting of the cleavage lines at the cephalic 

 end of the pupal envelope. A slit appears in the fourth segment 

 encircling the puparium, isolating an apical section of a cone 

 which is also divided by a median line. Usually one-half of 

 this raised cap serves as a lid which, opening, allows the fly 

 to escape. 



The subsequent development prior to flight is divided into 3 

 stages which are so graphically described by Newstead ^ that I 

 refrain from repetition, and refer the reader to his paper in 

 which this phase of the life history as well as many others are 

 treated with his usual faithfulness and clearness of description. 



In emerging, sometimes the imago is held at the anal segment 

 by a tissue which at first sight appears to be the lining of the 

 puparium. This is the exuvia of "the final ecdysis" (Newstead) 

 which the fly attempts to part with when it leaves the puparium. 

 In some cases the emergence is effected with the effete skin 

 intact, when it is plastered to the anal end of the fly and remains 

 attached even after the insect takes its initial flight. 



It has been observed in a few cases that if at this stage, prior 

 to the unfolding and hardening of the wings, the fly be immersed 

 in water for two minutes or more, development ceases. 



The sexes are readily distinguished upon emergence. The 

 female is invariably the larger and the lighter in color. It 

 emerges with its long tapering ovipositor projected until the 

 body drys thoroughly and flight is begun. 



To show the time required before a fly is able to take care 

 of itself after emerging, the following chronological note is 

 appended : 



Morning of April 30, 1912. 



9.35: The operculum has been split and the fly, a male, released from 

 the puparium. 



9.40: Length, 5 millimeters. 



9.42: The wings unroll and separate from the body, where they are 

 held while drying and hardening. Since emerging, the pro- 

 boscis is held against the notum between the 2 interlocking 

 processes of the mesotrochanters. 



9.52: The labellum of the proboscis is seen to change from the ultra 

 ash gray to brown, then to black. 



9.55: The entire labium becomes brown. 



9.58: The proboscis has been detached from the thoracic clasp through 

 movements of the legs. When released it gradually drops and 

 swings in place through traction by the longitudinal muscles. 

 This organ then assumes the normal position under, and 

 anterior to, the head. 



' Loc cit. 



