216 MEDICAL ENTOMOLOGY 



The five common species of Stegomyia may be distinguished by the 

 following Key: 



1 . Thorax with one or more white bands ....-., 2 

 Thorax with one or more white spots ........ 3 



2. Thorax with two median yellowish parallel lines and a curved 



white line on each side, the markings forming the so-called 



lyre pattern fasciata. 



Thorax black with a median white line .... scutellaris. 



Thorax with a median white line, and in addition, three 



parallel white bands on the pleura pseudoscutellaris. 



3. Thorax black, with three or four white spots . . . SUgens. 

 Thorax black, with two white lines at the anterior end, and 



a white spot on each side at the base of the wing . . africana. 



Stegomyia fasciata, Fabr. (Plate XXXVI, fig. 1). Head with dark 

 scales at sides, and median double band of white scales. Palpi black, 

 thin and long, with two basal white bands in the male ; in the female 

 short, and either tipped with white or entirely white. Thorax dark 

 brown to black, with whitish stripes simulating the shape of a lyre, 

 the two median bands often yellowish ; scutellum white. Abdomen 

 covered with black scales, the bases of the segments with white scales 

 forming transverse bands which extend round to the sides. Legs black, 

 femora with silvery knee spots; metatarsi with broad white basal bands; 

 the first tarsi of the fore and mid legs with a basal white band, the 

 others black ; first three tarsi of hind leg with broad white basal bands, 

 the last tarsi pure white. 



Stegomyia fasciata, commonly known as the ' Tiger ' mosquito, is 

 the invertebrate host of the parasite of Yellow Fever. When the female 

 sucks the blood of a person suffering from this disease during the first 

 three days of the fever, it becomes infected, and twelve days later it is 

 infective. When once it becomes infective it remains so for the rest of 

 its life, and is capable of transmitting the disease to a large number of 

 people. It is not yet definitely known whether the parasite can infect the 

 eggs, and thus the next generation. The virulent nature of the disease, 

 and the great danger of its spreading from its endemic centres in Mexico 

 and West Africa, have led to a most exhaustive study of the life his- 

 tory and habits of Stegomyia fasciata. 



The outstanding fact connected with the habits of this mosquito is 

 that it is a true domestic insect, and is seldom, it ever, 



Stegomyia 'fasciata founci more tnan 10 yards from inhabited houses; 



it prefers dark corners, and dark clothes, where it rests 



when not feeding. It frequently enters ships when they are moored 



