372 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I25 



after these months, to take full advantage of the larval peaks. How- 

 ever, since the larvae of this species are always present, thorough 

 control would require stream treatment throughout the year, based on 

 the 14- to 3 1 -day life cycle. Should control of S. metallicum and cal- 

 lidum also be undertaken, stream treatment would have to be repeated 



JAN FEB MAR APR MAY <IUN JUL AUO 8SP OCT NOV DtC 



Fig. 13. — Fluctuation in population of S. (L.) callidum throughout a year 

 period, expressed as the average number of specimens captured per collection 

 during month periods. (Prepared on 3-cycle semilogarithmic paper.) 



regularly, at about 28-day intervals. From the standpoint of onchocer- 

 ciasis control in the Yepocapa region, it is believed that both ochraceum 

 and metallicum control should be taken into consideration. 



NATURAL INFECTION OF ADULTS WITH 

 ONCHOCERCA VOLVULUS 



To determine which of the anthropophilic species play an important 

 role in the transmission of human onchocerciasis, it was necessary to 



