182 THE PIvANT WORI^D 



The Relations of Insects to Fungi. 



By Perley Spaulding. 



It has been known for a long time that there is a more or less inti- 

 mate relation between some of the insects and various forms of the fungi. 

 The really great importance of this relationship has not been realized 

 until recently, but within a few years it has been discovered that the re- 

 lation is of great importance, not only to the insects and fungi, but also 

 to the lower animals and even to man himself. The more familiar we be- 

 come with the life histories of the fungi the clearer it becomes that we 

 should know the exact relations existing between these two great groups 

 of organisms. And the more dangerous a fungus is to vegetable or ani- 

 mal life, the more imperative it is for us to realize to its fullest extent 

 the possible influence of our common and omnipresent insects upon the 

 status of the trouble. It is somewhat similar to Darwin's famous example 

 of the cats and the clover, in which he showed that the presence of a 

 large number of cats in a certain neighborhood may have a very decisive, 

 although indirect, effect upon the production of clover in that locality. 

 In the same way we see that, although at first thought there seems to be 

 little or no connection between such widely differing forms, there really 

 is a direct influence of the one over the other and vice versa. 



Many insects are appropriated by fungi as a base upon which to grow 

 and reproduce. Although insects have an external chitinous covering 

 which is, to a certain extent, impervious to the action of fungi, there are 

 certain weak places in this protective armor which make the entrance of 

 fungi a comparatively easy matter. These are the breathing pores and 

 the joints. A spore lodges upon the insect and finds there suitable con- 

 ditions for germination. The germ tube is sent out and makes an open- 

 ing into the interior of the body, where it branches and soon spreads 

 throughout the body. Fruiting threads are sent to the outside of the 

 body again so that the spores will be freely distributed as soon as ripe. 

 In any case the life of the insect is soon doomed, for the fungus finds its 

 best feeding ground in the vital organs and soon affects them so that 

 they can no longer carry on their proper functions. One class of 

 fungi grows on the outside of the insect's body and fruits while it 

 is alive, their attack upon the host seeming not to have such serious re- 

 sults. Cicadas, ants, locusts, chinchbuds, flies, bees, wasps, beetles, 

 moths, and butterflies are some of the best known of the insects which 

 are affected by these diseases. Spiders, although not insects, may also 

 be mentioned as hosts for fungi. The fact that insects have fungus 

 diseases is the most obvious connection between the two, and consequently 

 it has been longest known, and more work has been done on this phase 



