ON SOME ANIMAL PARASITES IN BRITISH GUIANA. 185 



A recent outbreak of Mai de Caderas {Trypanosoma equinum) amongst the sugar 

 plantation mules was in all probability propagated by biting flies, and most of the 

 common species of Tabanidae and other biting flies such as the well-known Stomoxys 

 calcitrans, L., were observed to feed freely on mules afflicted by this deadly equine 

 disease. 



The principal enemies of Tabanidae are several species of the large predaceous 

 wasps belonging to the Bembecinae. These, owing to their characteristic yellow and 

 black coloration and fierce habits, have received the pecuhar Creole name of " Cowfly 

 tiger." On the coast-lands the commonest species are Monedula signata, Latr., 

 M. 'punctata, Lep., and M. surinamensis, Dahlb., while in the forest area the formidable 

 M. pantherina, Handl., is frequently met with. Bemhidula discisa, Tasch., and 

 Bembidula variegata, 01., are also encountered in this region. 



Wherever Tabanidae occur, large numbers of these wasps will be observed to be 

 active, especially round cattle and mules when in the pastures. Despite the loud 

 buzzing flight and active darting movements of their enemies, the Tabanidae seldom 

 display any concern at their presence, though they take good care to choose those 

 portions of their host least exposed to the manoeuvres of the wasps. They are 

 always more numerous on sandy soils, which provide greater facilities for their 

 nesting habits. 



The Asilid fly, Mallophora calidus, F., is also an occasional enemy of Tabanidae in 

 the coastal area ; owing to its size however it is capable of attacking only the 

 smaller species. 



Dicranomyia cervus, Wied. A not uncommon species in some of the interior 

 districts. Readily attacks man. 



Chrysops tristis, F. This is a common species and is widely distributed throughout 

 the coastal region, it is occasionally met with in the forest area. It has a very 

 distinct tendency to attack man, and owing to its stealthy method of approach, the 

 first indication of its presence is usually the sharp pain caused by the insertion of its 

 proboscis, generally in some exposed part of the back of the neck. It is a shade- 

 loving species and is most active during the early morning hours and at eventide. 



Chrysops costafa, F. Only met ^vith in certain districts where the soil is of a sandy 

 nature and in the proximity of large areas of fresh water. It has the same tendency 

 to attack human beings as C. tristis and has much the same method of approach. 



Chrysops fulviceps, Wlk. Apparently only encountered in the forest area, and 

 nothing is known of its habits. 



Bolbodimyia hicolor, Big. Apparently an uncommon species. One specimen 

 was taken while attacking man in the North West District. 



Lepidoselaga a-assipes, F. One specimen of this handsome fly has been taken 

 on the coast-lands while attacking man. 



Diachlorus scutellatus, Macq. (fig. 2), D. podagriciis. F., D. curvipes, F. These 

 three species at certain times of the year are extraordinarily abundant, and during 

 these periods they become a most obnoxious pest, owing to their persistent and 

 bloodthirsty attacks on human beings. Their habitat is in the forest areas, especially 

 near the rivers in the North- West District. 



