TACHINOIDES IN BOKNU PROVINCE, NORTHERN NIGERIA. 



123 



Travelling Entomologist for the Research Committee. This belt, which also 

 appears to be a restricted one, lies along the com-se of the river Hawal, which 

 flows south-west into the river Gongola, a tributary of the Benue. 



I paid a visit to the district on 18th and 19th September, 1910, in consequence 

 of native information to the effect that 2 years ago, the headman of Dumboa and 

 his followers had gone into the district, about 30 miles from their town, for the 

 purpose of collecting taxes, and had taken with them about 20 horses. They 

 remained there only two days, and then returned to Dumboa. Within a short 

 time all the horses began to sicken, the chief symptoms being refusal of water 

 and food, and enlargement of the scrotum, with some slight swelling of the legs, 

 and within a period of three months every horse was dead. 



K^ 



Fig. 4. — Hawal valley, at Wajerou, South Bornu ; view from top of ironstone bluff 

 bounding the valley ; Glossina tachmoides was caught here on 18th September, 1910. 



The people of Dumboa did not appear to be acquainted with the appearance 

 of tsetse-flies, and they attributed the cause of the death of the horses to some 

 " very small thing that lives in the grass." On my announcing my intention of 

 visiting the spot to ascertain the cause of death of the horses, I was told that I 

 should not find anything, that the " small thing " was so minute as to be invisible 

 to the naked eye. Amongst the people living in the villages close to the river 

 itself, a belief was prevalent that the horses had died from eating some poisonous 

 grasses. 



The country here is much more undulating and well wooded, and during the 

 rains is hidden in long rank grass, which is burnt every year as soon as it is dry. 

 The river flows in a broad valley, bounded by ironstone bluffs and slopes, and 



