Plant Pests 367 



Nature of Injury. On the cyclamen (fig. 77, b), 

 the work of the mites produces a gall. Usually both 

 leaf and flower buds are badly affected. Infested 

 plants are stunted, the foliage distorted, and the 

 blossoms discolored. Instead of the normal soft 

 pink or red, the petals become blotched and 

 streaked; ultimately the flower wilts and dies pre- 

 maturely. On the geranium (fig. 77, a, and fig. 79, 

 b) the attack by the mite causes the foliage to curl 

 and to drop prematurely. Often, too, the injury 

 becomes noticeable as scorched spots on the leaves. 

 Injury is most severe when the plants are crowded, 

 the leaves touching each other, and the humidity 

 high. In this respect, therefore, the mite differs 

 from the red spider, in that the latter only thrives 

 under droughty conditions. On the snapdragons 

 (fig. 78, a and b, fig. 79, a) and chrysanthemums 

 the attacked foliage becomes curled and distorted, 

 and the flower buds, too, swell somewhat, and be- 

 come distorted and useless. The same pest also at- 

 tacks the blackberry out of doors (fig. 79, c). 



Control. At first, mites seem to attack the cycla- 

 men during dry weather. Later, however, poor cul- 

 tivation, poor ventilation, and excessive moisture in 

 the house seem to encourage the work of the pest. 



With geraniums some varieties seem to be more 

 resistant than others. Garman * states that the va- 

 rieties Le Pilote, Jean Vroud, S. A. Nutt, Alphonse 

 Ricard, Madame Kowalevski, Baron Grubissich, 



* Garriian, P., Maryland Agr. Expt. Sta., Bui. 208: 327-342, 

 1917. 



