MUSHROOMS 419 
pests are sometimes responsible for total crop failures. 
Small flies or gnats of various descriptions are among 
the most common pests. They are invariably present in 
untreated manure, and under favorable conditions mul- 
tiply very rapidly and soon become a great nuisance. 
High temperatures are especially favorable for the breed- 
ing of these pests, and therefore they are most likely to 
damage mushrooms in beds which have been spawned 
early in the autumn or before the advent of cold weather, 
for the flies are practically inactive at temperatures below 
55 degrees. The damage is caused by the larve of mag- 
gots passing up through the stipes and riddling the caps. 
Fumigation with tobacco (page 105) at the strength gener- 
ally employed in greenhouses will kill the adult flies. 
Hydrocyanic gas (page 109) may be employed before the 
beds are spawned. Bulletin 155, U. S. Bureau of Ento- 
mology, gives a description and life history of the various 
insects which feed on mushrooms. 
The mushroom mite (Tyroglyphus linteri) is always 
present in stable manure, and it may cause serious dam- 
age to the crop if the manure has not been properly 
composted. It multiplies most rapidly at high tempera- 
tures and in dry manure; this is an important reason for 
maintaining an adequate supply of moisture in the com- 
post pile. Apparently there is no practical means of 
eradicating the pests when they appear after the beds 
have been spawned. They feed both upon the spawns 
and upon the mushrooms. 
Springtails are very minute, grayish-black insects, 
which sometimes appear in great numbers upon the sur- 
face of the beds. These pests are most likely to be 
troublesome in damp, poorly ventilated houses or caves. 
They generally attack the mushrooms through the gills. 
Thorough ventilation, applications of pyrethrum powder, 
and the dusting of the beds and floors with quicklime are 
among the remedies recommended. 
