NO. I BLACK FLIES OF GUATEMALA — DALMAT 34I 



mentation with this group of flies and with other insects that have 

 resisted colonization. 



ZOOPHILIC SPECIES 



The preceding discussion in the section on ecology has been con- 

 cerned only with the anthropophilic species of black flies. Included 

 were those species that could possibly serve as vectors of onchocer- 

 ciasis because they either preferred biting man to other animals, or 

 because they commonly attacked man as well as other animals. Since 

 there is no species that attacks only humans, and since many of the 

 species that prefer animal hosts also attack man, it becomes evident 

 that no clearly defined distinction can be drawn. Thus, we can talk 

 of a species as being more anthropophilic or more zoophilic in its 

 feeding habits than another species. For the purpose of the present 

 discussion, those species that prefer biting animals other than man 

 have been allocated to the category of zoophilic species. According to 

 this definition, Simulium metallicum, callidmn, exiguum, and vera- 

 cruzanum should all be included, since only 5'. ochraceum is a strongly 

 anthropophilic species. However, since these species were already 

 discussed under the category of anthropophilic species, they will not 

 be treated here. 



Table 9 (p. 45) summarizes our data concerning the host preferences 

 of some of the zoophilic species, as well as similar data on the anthro- 

 pophilic species. Unfortunately, relatively little time could be given to 

 the zoophilic species since they were not involved in the transmission 

 of onchocerciasis. From the table it can be seen that there are some 

 definitely zoophilic species — that is, they bite only animals other than 

 man. 5*. acatenangoensis, mexicanum, pulverulentum ruhicundulum, 

 and smarti are such species. The strictly zoophilic nature of these 

 species can be considered reliable since, were the species to bite man, 

 they would have attacked the collectors while the latter were capturing 

 flies from animal bait, which they did not do. 



It would appear from the table that Cnephia pacheco-lunai might 

 bite man to the exclusion of other animals. This species has been 

 encountered almost entirely in a region above 8,ooo feet, uninhabited 

 by man. During the warmer daylight hours, sheep are taken up to the 

 region for grazing, so these animals probably represent the principal 

 host of pacheco-lunai. Unfortunately, since no collections of biting flies 

 were made from sheep or other animals in the region where pacheco- 

 lunai abounds, the hosts of this species could not be determined. The 

 single fly listed, which was fortuitously captured while biting a man, 

 can hardly be considered significant. The data on .J. haematopotum 



