272 FARM FRIENDS AND FARM FOES 



lice. During moist weather, which is especially favorable 

 to the growth of fungous diseases of insects, this aphid 

 parasite often destroys billions of victims, checking destruc- 

 tive outbreaks of crop pests. You can readily distinguish 

 with a lens the plant lice that are killed by the fungus from 

 those killed by insect parasites. 



A similar fungus is often very helpful in checking out- 

 breaks of the chinch bug, and has been the subject of 

 many investigations to determine whether it can be utilized 

 as a remedy for this insect. .Dead bugs covered with the 

 whitish, moldlike growth of the fungus may generally 

 be found wherever chinch bugs are abundant. While 

 probably the artificial propagation and dissemination of 

 the bugs hastens the spread of the malady, the success of 

 the measure is largely dependent upon the damp weather 

 favorable to the development of the disease. 



Fortunately these insect-killing fungi attack caterpillars 

 of many kinds. A short search among cabbages will often 

 show a cabbage worm killed by such a disease. The body 

 of the caterpillar is filled with the fungous threads which 

 convert it into a mummified condition, and finally produce 

 upon the surface a crop of spores. Many other insects, es- 

 pecially grasshoppers, are attacked by a similar disease. 



Caterpillar Fungi (Ascomycetes) 



Another group of these insect parasites attacks caterpil- 

 lars of many kinds, and are often called the Caterpillar 

 Fungi. They belong to the great group of Ascospore 

 Fungi to which so many diseases of plants belong. They 

 are readily distinguished by the strange, clublike projection 

 in which the ascbspores are developed. Two of these 

 mushroom-like bodies coming from a fly are shown in the 

 picture on the next page. White grubs are often killed 



