90 



Family Culicid.e. (Gnats and Mosquitoes.) 



'Culex sp. 



The adults of one or more mosquitoes were moderately common 

 about the sloughs. The larva? were not observed except in one of 

 the more stagnant bodies of water, but were probably present in 

 all. These insects pass the winter in the winged state, hid away 

 in crannies. The larvas swim head downward, and are the wrig- 

 glers of ueglected cisterns and rain barrels. The food during 

 ■aquatic life is probably decaying organic matter. 



Corefhra sp. 



The larvae of this genus are small, worm-like creatures, those 

 from Quincy about .32 inch long and .028 inch in diameter. The 

 body is cylindrical, tapering towards the posterior extremity. The 

 head is provided with a perplexing variety of structures for the 

 perception and management of food, including eyes, antennae, bit- 

 ing jaws, and a number of other tactile and prehensile appendages. 

 In front of the eyes the head resembles a truncated cone, and at 

 the blunt front extremity is attached a pair of antennae consisting 

 each of a long basal segment, from the free extremity of which 

 arise from three to live long, curved, and tapering rods. Near the 

 posterior end of the body is a series of long, plumose filaments. 

 The body is beautifully transparent in life, and within it may 

 be seen, near each extremity, a pair of pigmented, kidney-shaped 

 .respiratory sacs. 



The pupae may be distinguished from those of the next genus 

 by the presence on each side of the thorax of an odd, bladder- 

 like respiratory structiire, the two resembling a pair of ears. At 

 i;he posterior end of the body is a pair of large fan-shaped fins, 

 by means of which the pupae swim freely in the water. The 

 .adults are small, weak, obscurely-colored gnats, which are not 

 often observed. Two species of Corethra are recorded from this 

 country. 



Our larvae resemble those of the European Corethra pliimicornis, 

 but differ apparently in some details of form, — as in the shape of 

 the eyes, and of certain leaf-like tactile appendages in front of the 

 anouth. 



The eggs are laid enclosed in a gelatinous material, arranged 

 spirally in a single series in disk-shaped masses, and float at the 

 surface of the water till the young larv;^ emerge. This occurs 

 about a week after the eggs are laid, but probably the time varies 

 greatly with the temperature. 



Family Chironomid.e. (Gnats.) 



The familiar aquatic larvae of this family belong to the genus 

 C/hironomus. Probably no other one genus of insects constitutes 

 .as important an item in the food of as large a number of fishes. 



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