ARTHROPOD A 189 



skin where they cause lumps. Ultimately they develop and pass 

 out through the hide, riddling it with holes. Herms cites a case of 

 the ox warble in a child in which the grub, Hypoderma lineata^ 

 travelled from below the knee to a point behind the ear, taking 

 about two months' time. 



The sheep-bot flies, living in the nostrils of sheep and antelopes, 

 travel up the frontal sinus and cause the disease known as " stag- 

 gers." Other bot-flies attack rodents and even man. One form, 

 Dermatobia hominis, found in Mexico, Central, and South America, 

 attacks Birds, Mammals and Man. It is transported by certain 

 mosquitoes, particularly Psorophora lutzi. The larval period re- 

 quires about three months. 



Mosquitoes {Culicidae) ^ have slender sharp-pointed mandibles, 

 enabling them to puncture the skin of animals. Mosquitoes are 

 extremely important in the transmission of parasites causing disease. 

 They include three important groups: Anopheles, Aedes, and Culex. 

 (Figure 87.) 



In the Anopheliites, the head has upright forked scales and the 

 palpi in both sexes are almost as long as the proboscis. Anopheles 

 larvae lack a siphon tube and breathe through a stigmatic opening 

 on the eighth abdominal segment. They rest at the surface 

 of the water. In resting, as in the position of biting, the Anoph- 

 eles adult elevates its body in a characteristic manner (Figure 88). 

 Anopheles quadrimaculatus and several allied species transmit 

 malaria. Bird malaria is transmitted by the Culicine mosquitoes 

 {Culex pipieyts). 



In Aedes {Stegomyia) (Figure 89), the head has a few forked 

 scales and a mass of flat scales covering the head while the palpi 

 are less than one-half as long as the proboscis. Aedes larvae have a 

 short, conical siphon tube, and hang down from the surface of the 

 water. The successful completion of the Panama Canal was ac- 

 complished only after measures were taken to kill the yellow fever 

 transmitting mosquito, Aedes egyptii {Stegomyia calopus). 



In the Culicines, the head has a few flat scales, but many narrow 

 curved and upright forked scales. The palpi of the male are nearly 



1 Varro, the Roman author, cautions the builder against placing his farm-house 

 on swampy ground " because certain minute animals, invisible to the eye, breed there, 

 and, borne by the air, reach the inside of the body by way of the mouth and nose and 

 cause diseases which are difficult to get rid of." Centuries later mosquitoes were 

 proved to be the carriers of malaria and yellow fever. 



