124 MISC. PUBLICATION 631, U. S. DEPT. OF AGRICULTURE 



pagos Islands, Ecuador, Brazil, Peru, Bolivia, Paraguay, Chile, Argentina. 

 Palaearctic Region : Canary Islands, Madeira. Oriental Region : India. Ethiopan 

 Region: Zanzibar, South Africa (Transvaal, Natal), Seychelles. Australian 

 Region: Queensland, Wake, Samoa, Fiji, Society Islands (Tahiti), Hawaiian 

 Islands. 



Biology and Pathogenesis. — The larvae breed in various animal 

 and vegetable materials, such as human and animal cadavers, decayed 

 cotton seeds, dead locusts, feces, and kitchen refuse. Development 

 is rapid; the third larval instar may be attained within 3 days after 

 oviposition, and the complete life cycle may be completed in less than 

 3 weeks. Pupation takes place in the soil within a cocoon formed 

 of sand grains cemented together. 



This species has been recorded as involved in secondary wound 

 myiasis. It is probably of little importance. 



Literature. — Siddons and Koy (UfO) give an account of the life 

 history and immature stages. 



The Genus FANNIA Robineau-Desvoidy 



The generic name Homalomyia has been used in much of the older 

 literature on this genus. 



These are medium to small-sized flies ; the eyes are large, the cheeks 

 consequently narrow ; the proboscis is short. 

 There are two presutural and three post- 

 sutural dorsocentrals and two rows of acros- 

 ticals. Vein m 1+2 runs straight to the mar- 

 gin, the apical cell consequently being wide 

 open ; the second anal vein is short, the third 

 curved strongly forward in such a way that, 

 if the two were prolonged, they would inter- 

 sect (fig. 71). 



Life Histories. — The eggs, which are 

 provided with two broad sclerotized expan- 

 sions', are deposited on the medium in which 

 the larva is to live. There are three larval 

 stages. In the species for which the life his- 

 Figure 67. -Synthesiomyia tories have been worked out, development 

 nudiseta, posterior view 1S rapid when conditions are favorable, and 

 of last body segment of there may be two or more generations a year. 

 mature larva. The larvae breed in vegetable and animal 



matter in a somewhat advanced state of de- 

 composition, cadavers, excrement, fermenting foods, and rubbish in 

 the nests of birds and Hymenoptera ; sometimes they may parasitize 

 insects or vertebrates, although in the vertebrates parasitism is acci- 

 dental and in insects it is doubtful whether it may be considered true 

 parasitism. The mature larva leaves the semiliquid habitat to pupate. 

 Larva. — The larva is of characteristic form; the body is flattened, 

 narrowed anteriorly, and becoming broadest on the abdominal seg- 

 ments ; each segment beyond the first bears, on each side, a prominent 

 lateral process (usually longer on the posterior segments) which may 

 be either simple or pectinate ; the last segment bears three such 

 processes ; a row of similar but less prominent processes occurs on the 

 upper part of the ventral surface below this later row ; these processes 

 are missing on the last segment ; other usually less prominent but often 



