MUSHROOM PESTS AND HOW TO 

 CONTROL THEM 



By C. H. PoPENOE, Associate Entomologist, Tnicli-Crop Insect Inve.sti(jations, 

 Bureau of Entomology 



INTRODUCTION 



CULTIVATED niuslirooms are sub- 

 ject to attack by a variety 

 of pests, especially during warm 

 weather. Some of these may be 

 brought iuto the house in the compost 

 of which the beds are composed, at- 

 tacking the mushrooms through pref- 

 erence, while others feed normally 

 upon mushrooms, and are attracted 

 from the wild forms outside through 

 the greater abundance of their nat- 

 ural food plant in the cultivated beds. 

 Injury by these pests frequently be- 

 comes serious. This bulletin treats 

 of the measures for the protection of 

 the crop from such injury. 



The insect and other pests which 

 usually attack cultivated mushrooms, 

 and those of which complaints are 

 most frequently made, may be di- 

 vided roughly into four classes, 

 namely, mushroom maggots, mites, 

 springtails. and sowbugs. Of these the 

 maggots are tne most generally inju- 

 rious, the mites following in order 

 of importance, owing to the difficulty 

 with which their eradication is ac- 

 complished, and then come springtails 

 and sowbugs in the order named. 



MUSHROOM MAGGOTS 



The injurious forms commonly 

 known as " mushroom maggots " are 

 small, whitish or yellowish-white 

 maggots, usually having black heads. 

 They are the larvae, or young, of cer- 

 tain small, two-winged fungus gnats 

 or flies, usually l>lack or blackish in 

 color, and belonging to several spe- 

 cies.i They are minute, measuring 

 only about one-tenth inch in length 

 and about one-eighth inch in spread 

 of wings. They are rapid and pro- 

 lific breeders, especially during warm 

 weather, frequently occurring in 

 mushroom houses so abundantly as 

 to darken the windows. They may 

 be readily confused, however, with 

 gnats of the same genus which breed 

 in manui'e or in greenhouse soil, and 

 determinations of the species should 

 always be made by a specialist. 



The life history of a mushroom mag- 

 got is about as follows : 



The eggs, of which each female is 



capable of laying nearly 1,000, usu- 

 ally are deposited at the juncture of 

 the stem and cap of the mushroom or 

 in the manure or soil at its base. In 

 a warm temperature they may hatch 

 within three days, but in colder 

 weather this time is considerably ex- 

 tended. Upon hatching, the larvse 

 bore at once into the stem or cap of 

 the mushroom, soon riddling the cap 

 and causing the " breaking down " of 

 the mushroom. On account of the per- 

 ishable nature of their host they must 

 necessarily pass through their trans- 

 formations quickly. The larvae feed 

 from seven to ten days, by which time 



Fig. 1. — A mushroom flv, Aphiochaeta al- 

 Mdihalteris : Male. Much enlarged 



the entire cap is destroyed ; they then 

 enter the ground, each spinning a 

 slight silken cocoon just beneath the 

 surface, and pupate. The pupa stage 

 lasts from four to seven days, after 

 which the insects emerge as adults 

 and soon pair and lay eggs for the 

 next generation. Owing to the im- 

 mense number of eggs deposited and 

 to the short life cycle, the rapidity of 

 their increase is remarkable, so that 

 the presence of only a few insects in 

 the mushroom house at the beginning 

 of the season may result in millions 

 after the beginning of warm weather, 

 thus effectually preventing the culti- 

 vation of mushrooms. 



C.ONTROL 



Where it is possible to keep the 

 temperature of the mushroom house 



'The species attracting the most attention as pests are Sciara multiseta. Felt, Sciara 



agrnria F>lt, and Apliiocharta alhifJihaltenx Felt (see fig. 1). They belong to the two 

 families of flies known as Mycetophilidae and Phoridae. 



50985°— 25 1 



