274 



TSE-TSE.- 



-INSECTS.- 



-Piivtai.:mia. 



appears fortunately to be confined to particular districts, 

 and is usually fouiiil on hills, plains being free from it; 

 it is not much larger than the common house-fly, but 

 longer and of a blacker colour, with bars on its body. 

 Tlie attack of ten or a dozen is said to cause the death 

 of a horse; to oxen its attack is equally fatal. The 

 Tse-tse also at times attacks man ; but no danger fol- 

 lows — in fact, no more than from the bite of a ilea. 

 Man and all wild animals appear to escape with impu- 

 nity ; but the losses experienced through its attack on 

 domestic animals are quite appalling. 



Dr. Livingston describes the Tse-tse as remarkably 

 alert ; it avoids dexterously all attempts to capture it 

 with the hand at mid-day. In the cool of the morning 

 and evening it is not so agile. He says that its peculiar 

 buzz, when once heard, can never be forgotten by any 

 traveller whose means of locomotion are domestic ani- 

 mals; ''for it is well known that the bite of this poisonous 

 iiisect is certain death to the ox, horse, and dog. In 

 this journey, though we were not aware of any great 

 number having at any time lighted on our cattle, we 

 lust forty-three fine oxen by its bite. We watched the 

 animals carefully, and believe that not a score of flies 

 were ever upon them. 



" The mule, ass, and goat enjoy the same immunity 

 from the Tse-tse as man and the game. Many large 

 tribes on the Zambesi can keep no domestic animals, 

 except the goat, in consequence of the scourge existing 

 in their country. Our cTiildren were frequently bitten, 

 yet suffered no harm ; and we saw around us numbers 

 of zebras, buflaloes, pigs, pallabs, and other antelopes, 

 feeding quietly in the very habitat of the fl)'. There 

 is not so much difference in the natures of the horse 

 and zebra, the buffalo and ox, the sheep and antelope, 

 as to afford any satisfactory explanation of the pheno- 

 menon. Is not man as much a domestic animal as a 

 dog? The disgust which the Tse-tse shows to animal 

 excreta, is turned to account by some of the doctors. 

 They mix droppings of animals, human milk, and some 

 medicines together, and smear the animals that are 

 about to pass through an infested district. This, though 

 a preventive at the time, is not a permanent 

 protection. Inoculation does not insure im- 

 munity, as animals which have been slightly 

 bitten in one year may perish by a greater 

 numbei' of bites in the next. It is probable 

 that with the increase of guns, the game, as 

 happened in the south, and the Tse-tse deprived 

 of food, may become extinct simultaneously with 

 the larger animals. The ravages it commits 

 are sometimes enormous. Sebituane once lost 

 nearly the entire cattle of his tribe, amounting 

 to many thousands, by unwittingly intruding 

 upon the haunts of this murderous insect." 



We must refer briefly to the great benefits derived 

 by man through the agency of these insects. Diptera 



are the great removers or scavengers of all 



j)utrid animal and vegetable substances. No 

 sooner does an animal or plant die and begin 

 to decay, than it is resorted to by hosts of Diptera 

 which deposit their eggs immediately upon it ; and so 

 quickly are these hatched and the larvae full grown, that 

 a successive generation of flies continue to subsist upon 



the same food, until it is entirely consumed, and ihui 

 the earth is cleared of all offensive, and what would 

 probably prove infectious and injurious matter. Ex- 

 crement of all kinds, is in a great degree, removed 

 through their agency. 



We have only space left briefly to allude to some of 

 the more remarkable forms which occur in different 

 genera of Diptera. In the genus Asilus some species 

 from Brazil so closely resemble species of bees peculiar 

 to the same country, that it requires an amount of 

 entomological knowledge to distinguish the dillerence; 

 other species of Diptera exactly resemble wasps, into 

 whose nests they probably enter, being pjarasitic on the 

 larva of the wasp. Species of the genus VolluccUa, 

 parasitic upon Humble bees, very closely resemble the 

 bees themselves. 



One genus, Diojms (see Plate 11, fig. 7), may bo 

 mentioned as possessing a very remarkable peculiarity 

 of structure; the eyes in the species of this genus are 

 situated on pedicels half the length of the body of the 

 fly. These pedicels arise from the sides of the head, at 

 the usual situation of the eyes in ordinary species ; tiie 

 antennaj are situated near the eyes, one being on each 

 foot-stalk or pedicel near to the eye which forms its 



rig. 175. 





y \ 



AcUias maculipeuais. 



extremity. These species are found in Africa, India, 

 and in the islands of the Eastern archipelago. Fig. 

 175 shows a species of an allied genus Achius inaculi- 



Vvi. 170. 



rhytalniia cervicomis, gi'eatly magnified— a, male; h, female. 



pennis, and fig. 176, a, h, two outlines of a remarkable 

 species of the genus Phytalmia described by W. W. 



