1905.] Insects on Osiers and Willows. 



49 



the mushroom bed. In such cases, when the spawn commences 

 to " run," the threads, instead of having a clear and sharp outline 

 like white cord, present a fluffy appearance, due to the presence 

 of the parasite on the surface of the strands ; the branches are 

 also much fewer in number than when the spawn is healthy and 

 growing vigorously. 



Under such circumstances the entire bed should be removed 

 before the parasite produces spores, otherwise if the house 

 becomes thoroughly infected, common experience has shown 

 that the disease is exceedingly difficult to eradicate. 



When infection occurs through the introduction of spores into 

 the house by wind or other causes, the disease may be confined to 

 certain portions of the bed, and the prompt removal of infected 

 mushrooms as soon as the slightest symptoms are observed may 

 check the disease from assuming the proportions of an epidemic. 



After removing the soil and manure of an infected bed, great 

 care should be taken in the cleansing of tools, boots, and even 

 clothing; otherwise the risk of infecting other beds is great. 

 Rejected soil and manure should be at once removed from the 

 neighbourhood of mushroom beds. They may be applied to 

 the land, as the contained spores, so far as is known, can only 

 develop on some kind of fungus, and do not attack any other 

 cultivated crop. 



When a house or other structure in which mushrooms are 

 grown has become infected, it should be completely emptied 

 and thoroughly sprayed, both roof, walls, and floor, three times 

 at intervals of ten days with a solution of sulphate of copper- 

 one pound of the sulphate to fifteen gallons of water. 



During this period of spraying the house should be kept warm 

 and moist, for the purpose of favouring germination of the spores 

 of the parasite, which are destroyed with greater certainty when 

 growing than when in a resting condition. 



Willows grown at Kew Gardens have recently been attacked 



by the larvae of Cecidomyia saliciperda. Of Cecidomyidce^ or 



^ . Gall-Gnats, which attack trees, the most 

 Insects on Osiers ^ u , L f . ' 



and Willows. noteworthy and harmful are the species 



which infest willows. The place and mode 



of attack on the willow vary with the species of gall-gnat ; 



e 



