24 CIRCULAR 457, U. S. DEPARTMENT OF AGRICULTURE 



capable of doing a great deal of damage if they become established. 

 The adult females are by far the most common, and superficially 

 resemble the hypopi of some other mites, being oval, flattened, and 

 brown. When examined under a powerful magnifying glass a trans- 

 verse white or yellow band is visible. Little is known of the life 

 history of these mites except that under ordinary conditions the time 

 from egg to adult is about 10 days, and that they are parthenogenetic 

 in the same way that honeybees are, i. e., unfertilized eggs produce 

 males. These mites sometimes occur in enormous numbers, each 

 mushroom on the bed bearing a thousand or more. Although found 

 in the spawn, their tendency seems to be to work their way upward 

 to the surface. Besides eating the mycelium the mites chew minute 

 pits in the mushrooms, causing them to turn brown. Flame or hot 

 water should prove effective against these mites. 



Springtails 



Springtails are, in general, very small, gray, blackish, or brown 

 insects, ranging from about one sixty-fourth to one-sixteenth of an 

 inch in length. Beneath the abdomen of each insect there is a power- 

 ful springlike appendage which, when released, is capable of hurling 

 the insect through the air for a distance many times its own length. 

 In a wild state springtails live normally in damp places beneath rub- 

 bish and leaves, and most of them feed upon fungi. It is probable 

 that many of these "wild species," when once introduced into a mush- 

 room house, might prove to be serious pests. A number of species of 

 springtails are found frequently in mushroom beds. These include 

 Achorutes armatus Mc, Priostoma minuta Tull., P. simplex Fols., 

 Entomobrya sp., Xenylla weJchi Fols., X. humicola (O. Fab.) Tull., 

 Lepidocyrtus albicans Reut., L. cyaneus Tull., L. cyaneus var. cinereus 

 Fols., and L. lanuginosus (GmeL). All these are capable of doing 

 damage to spawn and mushrooms throughout the season. Two of 

 these springtails are shown in figure 10, A and B. 



Some growers have the idea that the presence of springtails in the 

 houses is to be desired; in other words, that springtails in numbers 

 are an indication of a good crop. This is possibly true to the extent 

 that conditions favorable to springtails also favor the growth of 

 mushrooms, but it is also true that these same favorable conditions 

 may allow the springtails to multiply fast enough to reduce the 

 crop materially. Springtails inflict damage by eating the spawn 

 and by chewing holes in the stems and caps of the mushrooms. 

 These pests are so easily overlooked that the grower frequently 

 attributes the reduction in yield to some other cause. 



The life history of these creatures is very simple. The minute 

 spherical eggs are laid in groups in the compost or spawn. They 

 hatch in about 10 days into minute replicas of the adults except for 

 their lighter color. After a period of growth and several molts, 

 these become capable of reproduction. Almost from the moment 

 they hatch from the egg they are capable of feeding upon and 

 damaging spawn and mushrooms. 



Springtails are usually brought into the houses with the com- 

 post, but may enter later through cracks. For this reason it is im- 

 portant that the surroundings of the mushroom houses be clean and 



