274 SOME NOXIOUS INSECTS. 



poisonous secretion, which causes a dull, throbbing pain 

 lasting for several hours. 



There are many species of "Water-Boatmen, but those 

 which belong to the genus Corixa, and can be known by 

 the flattened ends of their bodies, have the sharpest 

 beaka, the most virulent poison, and consequently are the 

 most noxious when handled. Even in England these 

 Corixee are apt to be rather unpleasant insects, but there 

 are some parts of Mexico where the lakes swarm Avith 

 Corixae of very much larger dimensions than any British 

 species. 



Yet these insects, noxious as we might think them, are 

 very useful to the comparatively uncivilised natives, who 

 eat, not the Corixse, but their eggs. 



At the proper time of the year the natives sink large 

 bundles of reeds in the water. In a week or two the 

 reeds are thickly covered with Corixa eggs, which are 

 scraped off and the reeds returned to the water. In fact, 

 the Corixa is treated very much like the mussel in the 

 French breeding beds. The eggs, after being scraped 

 off, are pressed into cakes, which are cooked and used 

 for consumption, under the name of "haoutle." 



Even the dread mosquito, the only insect which a 

 savage can have an excuse for ranking as noxious, is 

 really of direct value to some savage tribes. 



Livingstone mentions that -the shores of the Lake 

 Nyassa swarm with mosquitos. The late Mr. Baines told 

 me that no one who has not seen the mosquito swarm- 

 that hang on the banks of these African lakes, can form 



