1 88 FIELD ZOOLOGY. 



and often wingless; the young of these flies are born alive; 

 (2) those not living as parasites, body of the usual fly 

 form, and the young usually produced as eggs. 



The first division includes the bird ticks, the horse 

 ticks and the sheep ticks, flat- bodied insects with skin 

 more or less leathery, and with a single pair of wings; 

 these ticks, of course, have six legs. The animals more 

 rightly named ticks do not belong to the Insecta, but to 

 another entirely different division of the Arthropoda, 

 along with the mites. 



The second division comprises the true dipters; that 

 is, the typical insects -of the order, and this division has 

 much more numerous representatives than the first 

 division. Among the harmful dipters, we have 



Mosquitoes House flies 



Horse flies Stable flies 



Gallgnats Horn flies 



Bot flies Cabbage-maggot flies 



Beet flies Hessian flies 



Screw-worm flies Cheese skippers 



Fruit flies Onion flies 



And among the beneficial dipters may be mentioned : 

 Tacliina flies Syrphid flies 



Long-legged flies Bee flies 



Midas flies Wasp flies 



Dance flies Soldier flies 



Of the harmful flies mentioned, those which .are a 

 menace to the health of human beings are the mosquitoes, 

 the house flies, the stable flies, and the screw- worm flies. 

 (Fig. 77.) The so-called house fly that gives you a sharp 

 twinge as it pierces your skin with its stylets is not a 



