GALL GNATS 253 



striking thing is the discovery of the immense nmiiber of 

 species of mosquitoes. There have been many new species 

 discovered in the last few years. 



Gnats {Chironomidoe) . — Gnats are related to mosquitoes 

 and are interesting partly because of their close resemblance 

 to mosquitoes and partly because they occasionally multiply 

 so as to cause annoying contamination of reservoirs or 

 obstruction in water tanks. The antenna? are plumose as 

 in the mosquitoes but the mouth parts are different. The 

 larva? are more distinctly aquatic than the mosquito larvae — 

 can survive down in the water without coming to the sur- 

 face for air. Some live in mud — slender red, worm-like crea- 

 tures. One species is quite plentiful in the Northern States 

 especiallv near lakes and sometimes as abundant as the May 

 flies. 



Gall Gnats. — The next group is the one including the gall 

 gnats. It is a very important family with two or three very 

 important species. The most conspicuous of the galls 

 {)r()(luced by these is the cone gall produced on willow trees — 

 the pine cone willow galls. These are the result of the work 

 of the lar\'0e of the gall gnats. They are made up of a series 

 of leaves which o^'e^lap in the form of a pine cone. These 

 correspond with the leaves that would have come out along 

 the twig had it grown out normally. The leaves are devel- 

 oped close together and the larNje of the gall gnat is found 

 in a little cell in the centre of the gall. It issues in the spring 

 and deposits its eggs in the willow buds before the twigs 

 have started to grow, and the larvse hatch and form the galls 

 by feeding. There are a good many things in these galls 

 besides these larvae. Other insects find them a convenient 

 shelter, and other insects deposit eggs there. The tree 

 crickets are an example of this. These may be a little mis- 

 leading but they have nothing to do with the formation of 

 the gall. The pine cone gall is most conspicuous. There 

 is another species which simply produces an aborted growth 

 that looks like Brussels sprouts. 



The other species in this family to be mentioned are the 

 clover and wheat midges and the Hessian fl}'. 



