198 The Philippine Journal of Science "^^ 



flies under laboratory conditions in the veterinary research 

 laboratory at Alabang, Rizal. 



The writer had been unsuccessful in locating the eggs or 

 larvse in their natural habitats.^ Special efforts were made 

 during three months, prior to the appearance of the imago, to 

 find the young forms by searching plants and stones and by 

 using a water net along the course of the neighboring creek and 

 along the shores of the lake within a kilometer of the laboratory. 

 Except for the absence of this material, the local conditions 

 were ideal for the complete study of the bionomics of this species 

 of fly. At the foot of the hill upon which the research laboratory 

 is located, a lane of rain trees (Enterolobium saman Prain) 

 divides a pasture land from a low, wet area which drains into 

 the adjoining creek. The pasture land was used by a herd of 

 about 50 cattle which passed back and forth along one side of 

 the rain trees. The Tabanus when present used the cattle for 

 feeding and the rain trees adjoining for resting when engorged 

 or to escape from the sun's heat. During the early part of the 

 day, probably until 2 o'clock, the cattle were disturbed by the 

 attacks of many of these gadflies, which during the hottest 

 portion of the day and through the night rested on the trunks 

 of the convenient rain trees. Had the creek served as a harbor- 

 age for the eggs and young forms of the fly, the ecological 

 relations for a biological study of this fly would have been 

 complete. 



To obtain the eggs for study it was found necessary to keep 

 the flies in captivity in a structure built for this purpose. This 

 consisted of a capacious fly-proof building with brass-gauze 

 sides and top and cement flooring, sufficiently large for from 4 to 

 6 big animals. One section was provided with a concrete water 

 tank and growing plants. Here 2 carabaos were placed with 

 thousands of flies, which were gathered while resting on trees 

 along the road. In a short time females were observed feeding on 

 the hosts provided, and several were found ovipositing in various 

 places about the inclosure. 



OVIPOSITION 



The time selected for egg laying under the conditions pro- 

 vided was invariably during the early afternoon, never later 

 than 2 o'clock. This was observed in nearly 50 instances. 



' Subsequent to the writing of this paper, larvae and pupae have been 

 discovered in large numbers buried in sand at many points on the shore of 

 Laguna de Bay. 



