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TEXT-BOOK OF ENTOMOLOGY 



the branchiae is kept up by the flapping of the tail-pieces." The 

 larva of Helichus fastiyiatus is said by Leconte to be " very nearly 

 allied, while the remotely allied Stenelmis crenatus has no ex- 

 ternal branchiae. 1 



The larva of the mosquito also has two modes of respiration, breathing either 

 at the surface of the water through the two spiracles situated on the projection 

 (siphon) at the hinder end of the body which is thrust out into the air ; or when 

 at the bottom respiring by tracheal gills. The pupa also has a double mode of 

 respiration, either taking in air at the surface by the two thoracic horns with 

 stigmatic openings, or when submerged using its tracheal gills. 



Besides its long caudal tracheal air-tubes, the larval Eristalis is said by Chun 

 to thrust out from the anus a number (20) of short tracheal filaments which float 

 about in the water and serve to absorb the air. 



An aquatic Brazilian larva of the family Psychodidse has been 

 found by Fritz Miiller to take down under the water a large bubble 

 of air (Fig. 455, C), the main tracheal trunk ending each in an open- 

 ing at the end of the body (A, E) ; besides 

 this, while at the bottom it breathes by 

 three digitiform tracheal gills; another 

 species having two pairs (C, a). 



FIG. 466. Under side of body of larva of Blepharocera, showing the position of the tracheal 

 pills: A, section of the body through a sucker, showing position of the gills. , section of a 

 sucker : br, gill with numerous tracheae ; gl, outlet of excretory gland ; M. m. muscles. After F. 

 Miiller. 



The remarkable larvae of the Blepharoceridae (represented in the 

 United States by Blepharocera capitata), which live permanently in 

 swift streams, attached by median suckers to stones, are apneustic, 



1 Harris, Correspondence, p. 226, PI. III., Fig. 7. 



