334 



A N E CO NO MIC EN TO MO L OGY. 



never economically important. The minute species of Ceratcpo- 

 gon are furnished with piercing mouth parts, and are often ex- 

 tremely irritating, but otherwise the adults are harmless, unfitted 

 for blood-sucking. They are known as * ' sand-flies, " " punkies, ' ' 



"gnats," "midges," and by 

 Fig. 382. other names, some of which 



are applied indifferently to spe- 

 cies of diverse families. 



The ' ' fungus gnats' ' of the 

 family MycetophilidcE are also 

 small, mosquito-like creatures, 

 but,, more compactly built, with 

 shorter abdomen, stouter bodv 

 and legs, and antennae that are 

 not plumose or feathered in 

 either sex. They are smoky 

 or blackish in color, as a rule, 

 and frequent decaying vegeta- 

 ble matter or fungi, in which 

 the larvie feed. The latter are 

 slender, white, worm-like creat- 

 ures, with a distinct black head, and usually feed together in 

 considerable numbers. They sometimes develop a curious wan- 

 dering habit when full-grown, marching in rope- or ribbon-like 

 aggregations an inch or two wide and from six to ten inches 

 in length. Some bands have been observed from four to five 

 inches wide and twelve feet in length, piled up from four to six 

 deep ! Ordinarily no injury is done by these insects, which are 

 rather scavengers than otherwise ; but one species of Sciara 

 becomes a serious pest to mushroom growers, eating into the 

 plants and utterly ruining them. In fact, in many localities it 

 is simply impossible to grow mushrooms after warm weather 

 sets in. Measurable exemption may be secured by keeping the 

 houses or cellars tightly closed and fumigating frequently with 

 tobacco or pyrethrum to kill the flies. In a cellar the flies al- 

 ways get to any window or other source of light, and great masses 

 can be killed in such situations by a fine spray of kerosene emul- 

 sion diluted ten times. 



Quite recently Mr. Hopkins, of the West Virginia Experiment 



Chiyonumiis species, male, enlarged. 



