INSECTS INJURIOUS TO MUSHROOMS. 3 
quent entrance. These should begin with the construction of the 
house or cellar. The building should be so constructed as to permit 
of effective fumigation and should be fitted with tight screens of fine 
wire gauze, suitable to prevent the ingress of the fungus gnats. The 
gnats may also be brought into the house through the agency of the 
manure used in the compost beds, so that it is well to disinfect or 
sterilize this substance by means of steam. This may be accomplished. 
by placing the manure or soil in vats or boxes, through which steam 
pipes, perforated to allow the escape of the steam into the boxes, are 
conducted. (See fig. 2.) The manure should be heated to a tempera- 
ture of 150° F., which will destroy all animal life occurring therein. 
without injury to its capacity for producing mushrooms. Fumiga- 
tion with bisulphid of carbon just previous to planting the mushrooms 
is also productive of good results in destroying maggots in the com- 
post. The bisulphid should be used at a strength of 2 to 4 pounds to 
1,000 cubic feet of 
space and should 
be evaporated in 
shallow pans 
placed in the 
highest part of 
the house. It is 
very inflammable | 
and even explosive 
when brought into 
Fic. 2.—Steaming box, or sterilizer, for the treatment of com- 
contact with fire ost WSC atest) 
or sparks, so that care should be used to avoid bringing any fire 
into the building during the process of fumigation. 
- One of the best methods for the destruction of the adults or flies 
in their occurrence in mushroom houses is fumigation with tobacco 
or nicotine fumigants such as are used in greenhouses. These should 
be used in accordance with the directions indicated on the package 
for a medium or heavy fumigation.t. Used in this manner, and ap- 
plied once a week during the bearing season of the mushroom bed. 
this method has been so successful in reducing the number of flies 
that very little damage, if any, resulted from the larve. 
Fumigation with pyrethrum or dusting the powder over the beds 
is also effective against the mushroom maggots if taken in time, but 
tobacco fumigation may be considered standard for this use. 
1The proportion of nicotine in the several preparations varies to such an extent that 
no standard dose has as yet been formulated. 
