" FLIES " 289 



a simple calculation, it may be gathered that she may be the ancestor of 

 25,000,000 others in a single season. 



The House-fly is distinguished from others by its ashy grey colour the 

 male with some ochreous colour the thorax having four black cross lines. 

 The eggs are laid in dung and decaying refuse, often hatching in one day, 

 when the larva, a legless grub, begins to feed upon this putrid matter. 



It should be remembered, however nauseous it may be, that before the 

 fly begins to eat any fresh food, it first vomits up whatever is in its stomach. 



The Bluebottle, or BLOW-FLY, also lives on decaying matter, and without 

 doubt is useful as a scavenger ; but on no account should it be allowed in the 

 larder, or upon any human food. There is also a brighter-coloured fly known 

 as the Greenbottle Fly, more frequently seen sunning itself on bushes and 

 hedgerows. 



The Noonday Fly is larger than the House-fly, shining black, the male 

 having a bright yellow on the sides and under the head. Frequently seen 

 at midday round and upon trees. 



Other insects in this sub-order are the Cabbage-root Flies, very small 

 and injurious insects. The Sheep-ticks, or KEDS, and the Forest-fly are 

 viviparous, and suck the blood of mammals or birds. Others are parasites 

 upon bats, and others, like the Bee-louse, live upon bees. 



Order XVIII. SIPHONAPTERA. 



This order consists of the Fleas, which are entirely wingless insects, with 

 laterally flattened bodies, and with legs long and powerful, adapted for hop- 

 ping. They are capable of leaping two hundred times their own length. The 

 larvae live in and feed upon dust. 



Order XIX. HYMENOPTERA 



Saw-flies, Ichneumons, Ants, Wasps, and Bees insects with two pairs of 

 transparent wings. The name refers to a general characteristic which is of 

 great interest : The wings on each side are joined during flight by a series 

 of hooks on the margin of the hind-wing, which engage hi a groove or fold 

 in the fore-wing. This is easily seen if the wings (for example, of a bee) are 

 examined under the microscope. The females have elaborate ovipositors, 

 which in many cases have been modified into poison-stings. 



Sub-order i. SYMPHYTA. 

 THE SAW-FLIES. 



These insects have their ovipositor developed into a pair of saws, by which 

 an incision can be made into a leaf or stem, in which the egg is laid. There 



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