EXCURSIONS BEYOND EGA 479 



swarms of a kind of two-winged fly, the females of which 

 have a very long ovipositor, and which belongs to the 

 genus Stylogaster (family Conopsidse). These swarms 

 hover with rapidly-vibrating wings, at a height of a foot 

 or less from the soil over which the Ecitons are moving, 

 and occasionally one of the flies darts with great quick- 

 ness towards the ground. I found they were not oc- 

 cupied in transfixing ants, although they have a long 

 needle-shaped proboscis, which suggests that conclusion, 

 but most probably in depositing their eggs in the soft 

 bodies of insects, which the ants were driving away from 

 their hiding-places. These eggs would hatch after the 

 ants had placed their booty in their hive as food for their 

 young. If this supposition be correct, the Stylogaster 

 would offer a case of parasitism of quite a novel kind. 

 Flies of the genus Tachinus exhibit a similar instinct, for 

 they lie in wait near the entrances to bees' nests, and slip 

 their eggs into the food which the deluded bees are in the 

 act of conveying for their young. 



CHAPTER XIII 



EXCURSIONS BEYOND EGA 



November yth, 1856. — Embarked on the Upper Amazons 

 steamer, the 'Tabatinga', for an excursion to Tunantins, 

 a small semi-Indian settlement, lying 240 miles beyond 

 Ega. The Tabatinga is an iron boat of about 170 tons 

 burthen, built at Rio de Janeiro, and fitted with engines 

 of fifty horse power. The saloon, with berths on each 

 side for twenty passengers, is above deck, and open at 

 both ends to admit a free current of air. The captain, 

 or * commandante *, was a lieutenant in the Brazilian navy, 

 a man of polished, sailor-like address, and a rigid dis- 

 ciplinarian ; his name, Senhor Nunes Mello Cardozo. I 

 was obliged, as usual, to take with me a stock of all articles 

 of food, except meat and fish, for the time I intended to 

 be absent (three months) ; and the luggage, including 

 hammocks, cooking utensils, crockery, and so forth, 

 formed fifteen large packages. One volume consisted of 

 a mosquito tent, an article I had not yet had occasion to 

 use on the river, but which was indispensable in all ex- 

 cursions beyond Ega, every person, man, woman and child, 



