396 Mr. Brightwell on the Food of Corethra. 



Art. LIV. On the Food and Habits of certain Insects. 

 By T. Brightwell, Esg., F. L. S. 



Sustentatio larvarum, imprimis raping viventium, saepius singularis. 



Fabricius. 



I. Reaumur has investigated and described the metamorphoses of 

 the Corethra plumicornis,* a little Gnat of the family of the Tipulidce, 

 but this distinguished Naturalist was unable to determine the food of the 

 larva:; he conjectured that they devoured the invisible animalcula, 

 teeming around them in the stagnant waters which they inhabit. 



Reaumur found the larva in July and August in water. He describes 

 its body as transparent, almost cylindrical, largest at its anterior part ; 

 the head has in front a double hook ^crochet J. In the anterior part are 

 two reniform little bodies, and two others of the same kind, but smaller, 

 towards the anus. The last segment of the body has underneath an oval 

 fin CnageoireJ in the form of a leaf, and the anus is furnished with two 

 fleshy horns. The nijmpha is furnished with two little horns on the 

 head and two elliptical nageoires at the anus. It remains in this slate 

 only ten or twelve days. To this may be added that the viscera appear 

 to consist of a simple alimentary canal, largest in the centre of the body 

 where the food remains during digestion. The body of the animal con- 

 sists of innumerable crystalline fibres, woven together like net work. 

 It is more rigid than its appearance seems to indicate, and it retains this 

 rigidity to a remarkable degree after death. 



Accident made me acquainted, a few years since, with the fact that 

 these little animals devour, vdth astonishing rapacity, the Water Flea 

 f Monoculus Pxdex, Linn., Daphnia Pulex, Miiller) and that they are 

 an instrument, in the hand of Providence, for preventing iheir excessive 



* Corethra culiciformis, De Geer, VI. 372. t. XXIII. f. 4—12. Cor. plumi- 

 cornis, Reaumur, Vol. V. 40. Tab. VI. f. 4 — 15. Tipula chrystallina, De Geer, 

 149. 20? It is doubtful whether it be De Geer's insect: the respiratory horn 

 is wanting in our species. Cor. plumicornis, Mcigoi, Dipt. Eur. Vol. I. 15. 1. 

 Corethra lateralis, Latr. and Panz. 



