48 ECONOMIC ENTOMOLOGY 



acridiorum, but in other regions where the weather conditions are not 

 so favorable this method has not met with success. 



In the southern States the San Jose scale is often attacked by 

 SphcBrostilbe coccophila, but as a means of control artificial propagation 

 of the disease on a large scale has not been successful. 



Tent-caterpillars, brown-tail and gipsy moth caterpillars are de- 

 stroyed in large numbers by bacterial disease. 



Following is a list of the more important entomogenous fungi: 



Empii$a musccB on flies, E. grylli on crickets, etc. and E. aphidis 

 on plant-lice. Entomophthora aphidis on plant-lice, and E. sphcBro- 

 sperma on many caterpillars. Cordyceps militaris on larvae and pupae 

 of white grubs, wireworms and some lepidopterous forms. Most of 

 the conidial forms of Isaria and Sporotrichmn belong to the ascus 

 genus Cordyceps. 



Botrytis, Verticillium, Cladosporium, Mgerita and Fusarium attack 

 many kinds of insects, especially scale insects, plant-lice,, white flies, 

 and the chrysalids of moths. 



Future investigations will probably lead to the better utilization 

 of fungi in the control of many of the most noxious insects. 



Insects as Carriers of Plant Diseases 



Flea-beetles by eating holes in the leaves of potato permit the en- 

 trance of the spores of Early Blight {Macros porium solani) with conse- 

 quent partial destruction of the leaves. It has also been shown fairly 

 conclusively that certain aphids and other insects^ act as carriers of 

 Twig Blight {Bacillus amylovorus) of apples and pears, that the 

 beet leaf-hopper {Eutettix tenella) transmits to sugar beets the " Curly 

 Leaf" disease, and it is now believed that the squash bug {Anasa 

 tristis), the striped cucumber beetle {D. vittata), the 12-spotted cu- 

 cumber beetle {D. 12-punctata), the cucumber flea-beetle {Epitrix 

 cucumeris), the melon aphis {Aphis gossypii), and the 12-spotted 

 lady-beetle {Epilachna borealis) frequently inoculate the stems of cucur- 

 bits with the cucurbit wilt {Bacillus tracheiphilus). Again, the punc- 

 tures made by the plum curculio in plum, cherry and peach permit 

 entrance of the spores of the Brown Rot Disease {Sclerotinia fructigena) , 



^ Gossard mentions among others Aphis avencE, Empoasca mali, Eccoptogasler 

 rugulosus, and Lygus pratensis. "Any sucking insect can become a carrier, also any 

 insect with the bark-burrowing habit." 



