37 
HABITS AND STRUCTURAL CHARACTERS OF THE LARVA 
OF SIMULIUM* 
As the characteristics of the larvae of the European species of 
Simiilium are not likely to differ very materially from their tropical 
relations the subjoined notes may prove of some guidance to students 
in other parts of the world. The notes refer to a single specie-, 
Simulium ornaturn , Mg. 
Shallow rapid streams fully exposed lo the sun on hill sides, 
moors and open spaces in woods are the favourite resorts of these 
curious larvae. They are invariably found where the stream flows 
Fig 8.—Larva of Simulium ornatum in semi-erect position with the fan-like 
or fringed appendages expanded. x 6 J 4 - 
most rapidly; never in the side pools or in comparatively still water , 
and very rarely in those portions of a stream which are overshadowed 
by trees or shrubs. In streams where all the necessary conditions are 
available the larvae sometimes occur in countless numbers, covering 
the undersides of nearly every submerged leaf or blade of grass, and 
also, where not too much overshadowed by aquatic plants, on the 
stones and fragments of rock at the bottom of the stream. 
* These notes were compiled from observations made in I-.ngland and Helgumi 
in the summer of 1906.—R.N. 
