142 INSECTS. 



on each side when flattened for view as a transparent 

 object under the microscope; at the end are two 

 longer joints, the first having a small ring of shorter 

 hairs. 



The proboscis of the female is a very complicated 

 organ, consisting of six separate bristle-like pieces or 

 setae, all nearly of the same length. Two of these 

 are somewhat curved near the end, and provided on 

 the inside with fine teeth ; another pair consists of 

 very thin lancet-pointed instruments; then comes 

 another lancet-pointed seta, very sharp at the end, 

 and traversed by a canal ; next, a stouter and darker- 

 looking tube, slit up underneath, which serves to 

 contain the two toothed setae; and lastly, a stout 

 and broader sheath, also slit up throughout its length 

 beneath, in which all are packed. This sheath has 

 two lobes at the end, and has some resemblance to 

 the proboscis of the fly, of which organ it is the re- 

 presentative. 



The gnat lays its eggs in water. The eggs are 

 longish oval, with a kind of neck at the upper end ; 

 they are glued together side by side in large numbers, 

 and form a boat-like mass, floating on the surface 

 of the water. The larvae (PI. X. fig. 9) are very com- 

 monly found skipping through the water, or hanging, 

 as it were, by the tail from the surface. The head 

 is very broad ; and arising from each joint of the body 

 are tufts of hairs. Near the end of the body is a 

 tube which communicates with the tracheae; and 

 when the animal is quiet, this tube is brought to the 

 surface ; so that when the animal appears hanging to 

 the surface, it is breathing. In addition to this me- 

 thod of respiration, there are other respiratory or- 

 gans attached to the last joint of the body, consisting 

 of leaf-like plates ; hence these larvae have an aquatic 

 as well as an aerial respiration : the respiratory or 

 branchial plates also serve as a tail to aid in swimming. 

 Running down the back of the larva will be seen a 



