MYIASIS 225 



Other literature. The true B. depressa, however, is a very different 

 insect, the life-history of which is unknown, and there is no 

 evidence whatever to show that its larva is a subcutaneous 

 parasite." 



Dermatobia cyaniventris. 



The larvae of this fly cause subcutaneous myiasis in parts of 

 America, where it is fairly common in some places throughout 

 the tropical regions, especially near wooded lands. It also 

 occurs in Tonquin. The fly measures 14 — 16 mm. in length. 

 The head is yellow with prominent brown eyes, the thorax 

 greyish, and the abdomen dark metallic blue. The larva 

 penetrates the skin and produces an inflamed swelling with an 

 aperture through which seropurulent fluid, containing the black 

 faeces of the larva, exudes. In its earlier stages the larva is the 

 shape of an elongated pear with the posterior part of the body 

 much attenuated. The anterior border is ringed with several 

 rows of strong, black, recurved hooks. In its later stages the 

 larva is cylindrical, but stouter in its anterior half. Weil marked 

 hooks are present round the anterior segments, but not on the 

 last five segments. The larva is known as the ' Macaw-worm.' 



Infection of the orbital cavity has been described by 

 Keyt (1900) and Gann (1902). 



Various animals are also attacked. 



Duprey (1906) says that in Trinidad myiasis due to these 

 larvae is not infrequent, and believes that the larvae pass 

 accidentally from leaves, etc., into men and animals. 



Hypodernia. 



Occasionally larvae of flies belonging to the genus Hypo- 

 derma may produce subcutaneous myiasis in man. An 

 interesting case is recounted by Miller (19 10) in America. " In 

 December 1907, the boy noticed a small round lump just below 

 the left knee ; this lump was slightly red and very tender, 

 especially at night. About two days later the lump had 

 disappeared from its original position and was found some three 

 inches above the knee ; the following day it was still higher in 



G.-s. 15 



