,376 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 1 



Reuter for determination and were pronounced by him to be identical 

 with the species he had described as existing on grasses in Finland. 

 It therefore appears that P. dianthophilus Wolcott is a synonym of P. 

 graminum Reuter. 



Pediculopsis graminum Reuter appears to be a widely distributed 

 species in the United States. It has been taken from carnation buds 

 in Nebraska^ and in widely separated sections of Illinois.' In New 

 York state it is a rather common species upon several grasses, from 

 which it is probably distributed to carnation plants growing in the 

 field and subsequently is introduced into greenhouses. 



The work of the mite on grass and on carnations is quite dissim- 

 ilar. On grass it attacks the succulent stem within the sheath, just 

 above the topmost node. The growth of the stem at this point is 

 checked, causing the partially opened panicles to ripen prematurely 

 and giving rise to the condition known as silver top. The portion of 

 the stem which is attacked gradually shrivels and becomes twisted at 

 or just above the node. During the early spring a decay of the in- 

 jured portion of the stem is usually found. It always appears when 

 the area attacked is close to the ground, where the presence of moisture 

 is favorable for its growth. This decay is due to a fungus which 

 Prof. F. C. Stewart has determined to be Sporotrichum pom Peck. 



On carnation plants the mite does not attack the stem but works 

 into the center of the young buds. Here it introduces the same fun- 

 gus with which it is associated on grass. Experiments made for the 

 purpose of determining the point of attack indicate that the stamens 

 and pistils are first attacked and later the less tender tissues. The 

 fungus then finds a favorable condition for growth and in a compara- 

 tively short time the heart is entirely decayed and filled with mites, 

 while the growth of the buds is checked. 



The relation of the mite to the fungus is not entirely clear. It ap- 

 pears, however, that the mite visits healthy carnation buds for the 

 purpose of feeding on the tender tissues of the floral organs. Spores 

 of the fungus are thus introduced into the interior portions of the 

 bud, which eventually cause it to decay. The mites breed in this 

 decaying tissue and the subsequent generations migrate to healthy 

 buds, infecting them with the spores of the fungus. 



Probably the mite and its accompanying fungus will rarely be suf- 

 ficiently destructive to require special methods for their control. To 

 prevent unusual infestations it may be desirable to gather the in- 

 fested buds and burn them. The elimination of susceptible varieties, 



'Neb. Sta. Bui. 103. 1908. =J. J. Davis, Urbana, 111. 



