DIPTERA. BRACHYCERA. 369 



one-sixth of an inch in length, with clear wings, marked 

 near the tip with onehlack spot. This Fly, Sepsis cynipsea 

 (PL XVI., fig. 4), can hardly fail to be observed, owing 

 both to its great frequency and also to the peculiarity of 

 its manner and motions as it runs actively over the sur- 

 face of laurel and other leaves, with its glittering little 

 wings raised almost perpendicularly from its body, as if 

 in act to fly. The larva is a Scavenger. 



(Estridae, the last family of the Brachycera, is that 

 which contains the insects well known in their larval 

 stage under the name of Bots, Wurmals, &c. The .perfect 

 insects, or Bot-flies, are also called Gadflies, in common 

 with the Tabani, from which nevertheless they differ in im- 

 portant particulars. If, however, either of the etymologies 

 be just, whether that which assumes the Gadfly to be the 

 Goadfly, goading the cattle to almost a state of madness, 

 or that which considers it as the Fly which " makes the 

 cattle gadde up and downe with stinging them," both 

 Tabanus and (Estrus are fully entitled to the name. On 

 the approach of either, the herd of cattle, oxen, or deer, or 

 the flock of sheep, is thrown into the utmost terror and 

 dismay, oxen " gadding up and downe," while sheep herd 

 together in their sheepish belief that in numbers there 

 is safety. While, however, the attacks of the blood- 

 thirsty Tabanus arise from purely selfish motives, the 

 (Estrus approaches the terrified victim with another 

 end in view. Another end it is in more senses than one, 

 for no blood-sucking proboscis is hers while Tabanus 

 is fully armed with lancets and sucker, her mouth is 

 in a merely rudimentary state, and altogether incapable 

 of aggressive operations. Not so her long and sharp and 

 jointed, possibly also poison- dropping ovipositor. This 

 is her goad, this her weapon of attack and not care for 



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