36 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I25 



be taken into account. With this information, chemical control of the 

 adults becomes feasible. 



A study was undertaken to determine how the aquatic and semi- 

 aquatic vegetation might affect the distribution of Simulium species, 

 and which terrestrial plants might serve as diurnal and nocturnal 

 resting places for the adult flies. Plant samples were pressed and pre- 

 pared on herbarium sheets for identification. Two taxonomic lists are 

 given in Appendix I. The first contains those plants found in streams 

 serving as breeding places of Simulium species. These plants were 

 emergent from the stream bed itself, or grew along the margins of the 

 streams, their terminal portions trailing on the surface of the water. 

 Data in the lists indicate those species of plants found outside of the 

 onchocerciasis zone only, those found both inside and outside the zone, 

 and plants serving as substrata for pupae, larvae, and eggs of Simu- 

 lium species. The second list includes those plants that are commonly 

 found in the woodlands and in the cultivated portions of the coffee 

 plantations in the Municipality of Yepocapa, and indicates the plants 

 used as shade for the coffee trees, and those that serve as a resting 

 place for the adult Simulium during the daylight hours. 



Of the 121 plants listed as being associated with Guatemalan 

 streams, only 26 acted as anchorage for Simulium larvae and pupae. 

 Of these 26, 22 were found only within the onchocerciasis zones in 

 streams that favored the development of the anthropophilic species. 

 The three other plants, Tripogandra cumanensis, Hyptis sinuata, and 

 Ipomoea sp., which were found both inside and outside the oncho- 

 cerciasis zones, are rather broad-leaved plants. They contained pri- 

 marily larvae and pupae of species more commonly found outside the 

 zone which usually do not bite human beings. Renealmia aromatica 

 and R. strobilifera were used most often by the adults as a substratum 

 for deposition of their eggs. These findings seem to indicate that the 

 type of vegetation present in a stream may very well affect the Simu- 

 lium- fauna found therein. Although much more extensive plant collec- 

 tions were made within the onchocerciasis zones, enough were made 

 outside of the zone to warrant mention of these observations. 



Eighty-eight terrestrial plants were identified. The adults of Simu- 

 lium ochraceum, S. metallicwm, S. callidum, and 5. downsi were found 

 resting on the leaves of the following plants : Ricinus communis L. 

 (higarillo), Polymnia maculata Cav. (shorotot), Inga punctata 

 Willd. (cuxim), Inga leptoloba Schlecht. (caspirol), Inga micheliana 

 Harms (chalum), Lueuma salicifolia H.B.K. (zapotillo), Casuarina 

 equisetifolia L. (cipres), Bunchosia cornifolia H.B.K. (cereza), 

 Tabebuia pentaphyla (L.) Hemsl. (mano de Leon), Sideroxylon 



