336 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I25 



It might be reasoned that flies found biting in the trees were at- 

 tracted there by the desire for a blood meal. However, the finding of 

 flies actually resting in the trees would indicate that they naturally 

 occur in this habitat. This should be expected since flies would prob- 

 ably choose such sites for stops during the long flights of which they 



Table 22. — Record of flies resting in trees 



Data represent the duration of resting periods of flies observed at various 

 altitudes in trees and on different surfaces 



Surface 

 Altitude on which 

 (feet) resting 



13 Branch 



16 Leaf 



18 " 



18 " 



18 Branch 



19 Leaf 



19 " 



24 " 



27 " 



27 " 



27 " 



28 " 



29 Branch 



29 " 



32 Leaf 



36 " 



36 " 



37 Branch 



19 Branch 



28 Leaf 



35 " 



37 " 



139 " 



I 43. 



Num- 

 ber of 

 speci- 

 mens 



.Leaf 



Duration 

 of resting 



period 

 (minutes) 



5-0 

 2.0 

 2.0 

 5-0 

 7.0 

 4.0 

 S.o 

 0.08 

 i.o 

 4.0 

 6.0 

 0.07 

 0.1 

 0.27 

 30 

 16.0 

 2.0 

 0.08 



8.0 

 0.4 

 1.0 

 30 

 2.0 



50 



Surface 

 Altitude on which 



(feet) resting 



40 Branch 



40 " 



41 Leaf 



43 " 



43 " 



45 " 



46 " 



46 " 



46 " 



46 Branch 



47 Leaf 



50 Branch 



50 " 



50 Leaf 



51 " 



55 " 



112 " 



40 Leaf 



46 " 



47 " 



47 " 



51 Branch 



Num- 

 ber of 

 speci- 

 mens 



Duration 

 of resting 



period 

 (minutes) 



0.07 



0.5 



1.0 



30 



0.4 



30 



4.6 



0.5 



4-5 

 o.is 

 50 

 0.47 

 30.0 

 0.08 

 0.4 



7-5 

 30 



0.66 



0.25 



0.4 



30 



0.21 



are capable (see "Flight Range and Longevity" in this section). Thus, 

 in planning control of adult flies, the ground surface, as well as all 

 levels of vegetation, should be taken into consideration. It would ap- 

 pear to be plausible to use airplane treatment to reach the resting flies. 

 However, the very rugged terrain in the onchocerciasis regions, ir- 

 regularly interrupted by deep gorges and high cliffs, makes such 

 methods almost impossible. In addition, the dense canopy of vegeta- 



