II 



FLIES WITH AQUATIC LARV^ 



165 



from its body. There are four 

 rows of these, and each ends in 

 two points. This little aquatic 

 worm constitutes the favourite 

 food of more than one Insect, 

 which pursue it, as the larva 

 of the Tiger-beetle does the 

 Earthworm. I have lately in- 

 vestigated the structure and 

 habits of a Dipterous larva 

 which lives upon Tubifex. This 

 is the larva of Dicranota. The 

 full-grown larva is about three- 

 quarters of an inch long, and of 

 a dirty white colour. Com- 

 monly it buries itself in gravel 

 and mud, and may be fished 

 out of the bed of a stream con- 

 taining Tubifex. It creeps with 

 some rapidity through the mud, 

 and rarely exposes itself to view. 

 It can also swim about in the 

 water with a lashing or serpen- 

 tine movement not unlike that 

 of the Chironomus larva. Now 

 and then it leaves the water 

 altogether. The food of the 

 Dicranota larva is readily ascer- 

 tained by observing that the 

 stomach contains a red sub- 

 stance after Tubifex has been 

 supplied to it. The peculiar 



rO 



Fig. 50. — Larva of Dicranota 

 bimaculata. This and fol- 

 lowing figs, are copied horn 

 a paper by L. C. Miall in 

 Trans, Entom. Soc, 1893. 



