234 SOME MINUTE ANIMAL PARASITES 



be burned. A painter's lamp should be used over all 

 the woodwork of infected hives before new stocks 

 are placed in them. The soil around infected hives 

 should be removed to a depth of several inches and 

 burned, and the surface should then be limed heavily. 

 It is unwise to unite weak stocks, and also inadvisable 

 to import stocks from a disease-free area into an 

 infected one. The new-comers usually succumb 

 quickly. On the other hand, there is more chance 

 of success if bees from one infected area are moved 

 into another, as there is the possibility that some of 

 them have acquired partial immunity. It seems 

 wisest to destroy all infected stocks as soon as the 

 disease is detected, and, having taken due precau- 

 tions, to re-stock. 



Microsporidiosis has the greatest economic im- 

 portance in connexion with silkworms and bees, 

 but various members of the Microsporidia are found 

 in other insects and in fish. Among the chief foes 

 of moths and of bees are various Ichneumons, insects 

 which destroy the bee gradually by laying their eggs 

 in the abdomen of the victim. The grubs then 

 develop within the living bee or moth, and ulti- 

 mately kill it. One of these Ichneumons, Stenich- 

 neumon trilineatus, is parasitic on the caterpillars of 

 the common gooseberry moth, Abraxas grossulariata, 

 but it, in turn, may fall a victim to a newly discovered 

 Nosema, N. ichneumonis, which lives in the intestine 

 and the fat body of the adult. This, then, presents 

 an example of hyperparasitism, for the parasitic 

 insect is itself the victim of a protozoal parasite. 



It has been suggested that N. apis might possibly 



