848 



THE DIPTERA 



with twelve segments, armed with minute spines. It is most 

 active, and burrows into the tissues of the affected animals or into 

 the mass of putrid flesh or decaying matter. It grows rapidly 

 and matures in from five to seven days, when it endeavours to 

 escape from the wound or cavity on to the ground, when it 

 wriggles off and buries itself in the ground at a suitable place, and 

 becomes the brown cylindrical pupa with rounded ends. The pupa 

 is about f inch in length, and matures in some nine to fourteen 

 days. 



Habits. — It is a pest to man and animals. 



Distribution. — America, from Canada to Patagonia, but most 

 common in the tropical and subtropical belts. It is killed by cold 

 winds. In the Southern United States it occurs from July to October . 

 It is also found in the W est Indies. 



Pathogenicity. — It attacks cattle after castration, spaying, 

 branching, dehorning, and when wounded by ticks or barbed wire. 

 It will enter the uterus if there is placental retention, and will attack ' 

 the navels and mouths of young calves. Horses and mules may 

 be attacked in the sheaths and vaginae, and in the navel in colts. 

 Hogs are especially liable to be attacked, but sheep rarely, unless 

 after being worried by dogs. Man is attacked when sleeping in 

 the open air, and more rarely when driving. The symptoms pro- 

 duced in man will be detailed later under Nasal Myiasis in 

 Chapter LXVII. 



Treatment. — Injections of chloroform water are the best means of 

 getting rid of the larvae, but the frontal and other sinuses may have 

 to be opened to remove them if in large numbers. 



Prophylaxis. — The use of mosquito curtains and protection to 

 the nose by handkerchiefs are important in man. Wounds, of 

 animals should be washed with weak carbolic lotion and dressed 

 with pine tar or oakum and tar. 



Chrysomyia vlridula. 



Causes nasal myiasis in Central America, and will attack ulcers. 



Pyenosoma Brauer and Bergenstamm, 1893. 



The larvae of Pyenosoma putorium Wiedemann, 1830, are said to 

 be parasitic in man and the domestic animals in Abyssinia, the 

 Belgian Congo, and Lorenzo Marques. 



This fly resembles Chrysomyia, but the three dark stripes on the 

 dorsum of the thorax are wanting. 



Pathogenicity. — It causes nasal myiasis in man, while other 

 species — e.g., P. megacephala and P. marginale, etc.- — are found in 

 cattle. 



Lucilia Robineau-Desvoidy, 1830. 

 Flies of this genus — e.g., L. cessar Linnaeus and L. sericata — deposit their 

 eggs on ulcers. L. nobilis Meigen has been found in the auditory meatus. 

 According to Peiper, L. cessar Linnaeus and L. regina Macy have been recog- 

 nized as, causes of intestinal myiasis. \ 



