42 The Philippine Journal of Science wn 



My attention was attracted by the peculiar grouping of the 

 ectoparasites; groups of from 2 to 5 predominated. On closer 

 inspection the group was found to consist almost invariably of 

 more than 1 species, a Stomoxys usually being the central figure. 

 Where a Stomoxys was lacking, it was found that the group fed 

 from a common area with the heads of the individuals in close 

 contact. The food of these flies was found to be a droplet of 

 freshly exuded blood, and among the blood imbibers often not an 

 individual belonged to a species with a piercing mouth; they 

 consisted principally of house flies. Other groups of flies sur- 

 rounding a Stomoxys attracted attention by the fact that while 

 it was feeding the rest waited. The latter gave evidence of 

 great impatience and eagerness in the movements of nudging one 

 another and colliding with the Stomoxys, apparently making 

 efforts to dislodge it. The Stomoxys having been satisfied, the 

 other flies pounced upon the feeding spot where trickled a well- 

 rounded blood drop. These flies collected around the puncture, 

 and lapped the blood as it oozed from the wound. In a moment 

 the group disbanded with abdomens more or less reddened and 

 distended, the individuals either flying off the host to rest or 

 to join another biting Stomoxys. In many instances the Sto- 

 moxys was accompanied by a single fly which hovered above it 

 until the Stomoxys was fully engorged and left the exuding 

 blood to the disposal of the second passive parasite. 



THE OCCURRENCE OF STOMOXYS CALCITRANS IN NATURE AND ITS 



RESTING HABITS 



Stomoxys calcitrans is essentially a parasite of live stock, and 

 the natural occurrence of the fly is related to these domesticated 

 animals and their environs. The resting habits of the stable fly 

 are quite characteristic and related in a measure to the feeding 

 habits. It may be found at almost any time of the year in these 

 localities feeding several hours before 8 o'clock in the morning 

 by which time it in many instances has engorged itself. At about 

 this time many may be found at rest either upon a part of the 

 animal inaccessible to the host, or more commonly upon trees and 

 fences bordering corrals and sheds. 



I have found that in this locality the most frequent resting 

 place is the interwoven cross-wire fence, a small section of which 

 will accommodate from 4 to 6 flies. The fly is perched usually 

 away from the sun under the wire with its head directed toward 

 the shaded side. All the feet clasp the wire, and the proboscis is 

 slightly drooped. So immobile are they that when the fence is 

 violently shaken few flies are disturbed. They are so sluggish 



