Mushroom Pests and How to Control Them 



Besides the injury to the mycelium, 

 mushroom mites cause damage to the 

 fruiting bodies by eating into them, 

 distorting or destroying tlie younger 

 growth. In the more mature mush- 

 rooms the mites may be found clus- 

 tered in groups consisting of indi- 

 viduals of many sizes, usually hidden 

 in the folds between the gills, where 

 they burrow into the tissue, causing 

 the caps to break down. 



No direct observations on the life 

 history of this species have been made, 

 but judging from that of related spe- 

 cies it is about as follows : The eggs, 

 which are large in proportion to the 

 size of the mites, are laid in or about 

 the mycelium or on the young devel- 

 oping caps. They hatch in a short 

 time into the characteristic 6-legged 

 young, which soon become mature. 

 The time from the deposition of the 

 egg to the maturity of the mite has 

 not, so far as the writer knows, been 

 worked out accurately, but it undoubt- 

 edly occupies only a few days. It is 

 on this account that the mite is able to 

 increase so rapidly, apparently as if by 

 magic, and thus give rise to the theory 

 of spontaneous generation sometimes 

 advanced to explain this condition. 



Under certain conditions the hypo- 

 pus, or migratory, stage is produced. 

 This stage, so far as known, is pecu- 

 liar to the family Tyroglyphidae, to 

 which this mite belongs, and is very 

 remarkable. The mite develops a 

 hard, chitinous covering, has no mouth 

 parts, and is provided with short legs 

 insufficient for walking. On the ven- 

 tral surface of the body is an area 

 provided with sucking disks, by means 

 of which the hypopus attaches itself 

 to an insect and is so transported to 

 suitable breeding grounds in other lo- 

 calities. On arrival at a suitable 

 breeding place the mite detaches it- 

 self from its insect host, molts, and 

 soon becomes adult. During the hy- 

 popus stage the mite takes no food 

 and causes no injury to the insect 

 which carries it. This peculiar stage 

 is the natural means for the distribu- 

 tion of the mite to new localities and 

 is in many cases responsible for its 

 appearance in localities far from pre- 

 viously infested beds. 



In addition to the means mentioned 

 above the mite may obtain access to 

 mushroom houses in infested compost 

 or in spawn from infested houses. 

 The greater part of the infestation, 

 however, probably takes place through 

 the agency of the small flies which 

 frequent mushroom houses and which 

 carry the hypopus stage of the mite 

 from one house to another. 



REMEDIES 

 Little can be recommended for the 

 control of the mushroom mite after it 

 has once become established in a 

 house. Owing to the absence of 

 breathing pores it is practically un- 

 affected by fumigants suitable for the 

 control of other mushroom pests, and 

 applications of sulfur, tobacco dust, 

 and other insecticides to the beds seem 

 only to prove slightly inconvenient to 

 the mite. It is one of the most stub- 

 born pests encountered in mushroom 

 culture and may be brought into the 



Fig. 2. — The mushroom mite (Tyroglyphus 

 lintneri). Highly magnified. (Banks) 



house in almost any manure that is 

 used for the bed. When in the hypo- 

 pus stage it is capable of prolonged 

 suspension of vitality and is likely to 

 remain in the house for an almost un- 

 limited time without death. The only 

 measures, therefore, that may be con- 

 sidered are those of prevention. 



When an infested house is to be 

 cleaned all compost should be gathered 

 with the utmost care, removed to the 

 outside, and thoroughly disinfected by 

 drenching with boiling water, or it 

 may be hauled to a distance and 

 spread upon the ground as fertilizer 

 or destroyed by burning. The ground 

 occupied by the mushroom beds should 



