6o6 



INSECTA ORDER DIPTERA. 



latter case, however, it is possible that they feed on other insects which 



live in the wood, and not on the wood 

 itself. 



The species of the family Empidce much re- 

 semble the Asilidce in habits, but are smaller, 

 and frequent woods rather than open places. 

 They will, however, feed on vegetable as well as 

 animal substances, and their larvae live in loose 

 earth. 



The BombyliidcE, or bee-like flies, are another 

 interesting family. They are moderate-sized 

 hairy flies, much resembling bees, but with a 

 long straight proboscis, with which they suck 

 the honey of flowers. The larvae are parasitic 

 on the earlier stages of other insects. 



The Syrphidce are a large family of hand- 

 somely - coloured flies of moderate size, which 

 curious hovering and darting flight. Many 



Fig. IQO.Asilus crabroniformis. 

 Nat. size. 



Fig. lOl.Eristalis tenax. 

 Nat. size. 



are remarkable for their 



of the species resemble wasps and bees ; and 

 their larvae live on decaying animal or vege- 

 table substances, and frequently in foul water. 

 The most interesting species of this family is 

 Erisbalis tenax (Linn.), a blackish fly, more or less 

 clothed with tawny hair, and rather more than 

 half an inch long. Its larva is often found in foul 

 water, and is called the rat-tailed grub, from a 

 long respiratory appendage at the end of the body. 

 This species appears to have given rise to the wide- 

 spread belief that bees might be reared from dead 



carcases, as we find recorded in the story of Sampson ; in the ' ' Georgics " of 

 Virgil, and in many other old writings. Wasp-like flies of similar habits 

 have also given rise to the idea that wasps or hornets were, or might be, 

 bred from the carcases of horses. 



The (Estridce, or bot-flies, are chiefly remarkable for being parasitic in 



mammalia. Recent statistics have shown that the amount of damage caused 



by the following species to cattle in England alone is quite 



Family CEstrjdce. astounding. Hypoderma bovis (Linn.) is a black hairy fly, 



Bot-Flies. varied with whitish and yellowish, which attacks oxen ; it 



is about half an inch in length. The flies themselves are very 



rarely seen, unless when reared. Other species of this family live in the nasal 



fossae of sheep and deer ; in the stomach of the horse ; and in various other 



situations. They have sometimes been known to attack man, especially in 



warm countries ; but whether any species of this family habitually attacks 



man is doubtful. Hypodermic dipterous parasites which infest man belong, 



as a rule, to some section of the immense family Muscidce, which we have 



now to consider. 



The Muscidfx include nearly half the known Diptera. and have nearly all 

 more or less resemblance to the common house-fly, which is the type of the 

 whole order. The antennae are always three-jointed, with 

 Family the third joint compressed, and bearing a bristle on the 



Muscidce. back, which is often plumose. The proboscis is always pre- 

 sent, and is usually membranous, rarely horny; the palpi 



