38 The Philippine Journal of Science ww 



10.00: The length of the fly, including the projection of the labium, has 



increased to 5.5 millimeters. 

 10.03 : The fly makes its initial flight inside of the flask. 

 10.10: The proboscis is now jet black and fairly hard. 



From these notes it can be seen that it requires one-half hour 

 of drying before the insect is able to fly and also that it would 

 be impossible for the fly to apply its proboscis in feeding for 

 an equally long time after emergence. 



The difference in the time of emergence of flies from the 

 same lot of eggs is usually out of all proportion to the difference 

 of time of deposition of the eggs. The larvae from a lot of eggs 

 laid by a collection of females on June 24 to 26 commenced 

 pupating July 2 and emerged July 15. Emergence continued 

 daily up to July 26, fully eleven days after the first appearance 

 of flies. It was noticed that the flies appearing last were fully 

 1 millimeter smaller than those appearing first. This was due 

 perhaps to the gradual drying of the food medium which was 

 less suitable for nourishing the larvae hatching last. 



This difference in size is seen also in flies of precisely the 

 same age. This was noted in 2 females emerging April 4, fed 

 daily upon the same animal. When 20 days old they measured, 

 respectively, 5.5 millimeters by 2.5 millimeters, and 7 millimeters 

 by 3 millimeters. 



FEEDING HABITS OF STOMOXYS CALCITRANS 



In my experience the adult fly, male and female, can be kept 

 alive only by feeding on the blood of animals. Drawn blood, al- 

 though accepted, apparently does not answer the requirements 

 of the fly, even when renewed daily. Flies nourished in this 

 manner usually do not survive longer than flies kept without 

 food. 



Under laboratory conditions flies of this species will feed for 

 the first time six to eight hours after leaving the puparium, 

 but I do not doubt that, in nature, blood is taken as early as 

 one hour after emergence. Several laboratory-bred flies have 

 been seen feeding in an apparently half-hearted fashion for a 

 few minutes within one hour after emerging. 



Judging from observations made under experimental condi- 

 tions, Stomoxys is essentially a blood feeder; it has never been 

 observed to take plant juices, although it sips water when con- 

 fined in jars and test tubes. 



Under conditions obtaining in these Islands, the fly will feed 

 readily on man, although it rarely attacks him in the presence of 



