Aug. 20. I9I7 Cyclamen Mite 387 



the light was bright, using the young tender foliage, the older leaves 

 being stripped from the corms. The petiole of each leaf was surrounded 

 with vaseline to confine the mites to the leaves. The mites are negative- 

 phototactic, always endeavoring to get away from the light. They 

 curled the tender young leaves in striving to seek crevices, and some 

 even dropped to the soil and, hence, would not propagate successfully 

 in the lighted places. Where crevices were cut in the leaf, only the 

 covered eggs embedded in the crevice hatched, the uppermost eggs 

 shriveling and dying. The eggs being so embedded in the crevice or 

 in the curled leaves made it impossible to get data desired on the various 

 stages. It was therefore thought that, since the mites were negative- 

 phototactic, it would help if the individual plants were covered with 

 battery jars surrounded with black paper. This proved quite satis- 

 factory to establish the mites on the leaves, which were of medium 

 size, and to study the habits of the species as the eggs in many cases 

 were deposited on the surface exposed under the dark jar, and the in- 

 cubation and habits of the succeeding stages could be studied. This 

 also confined the moisture, but the darkening of the plant might, in cases 

 where the plant is not sufficiently vigorous to withstand the period 

 necessary to run a generation through, so diminish the chlorophyll in 

 time as to cause the plant to die. It is necessary, therefore, that the 

 plant be uncovered at intervals to prevent such an occurrence. 



REMEDIAL CONSIDERATIONS 



As most of the species of mites no doubt have an extremely primitive 

 respiratory system, it is often difficult to control them satisfactorily by 

 fumigation with various gases; hence sprays must be resorted to as a 

 control measure. After the older cyclamen plants become badly 

 infested there is not much hope of saving them, as the mites are usually 

 concealed under the calyx and even to the inner flower parts of the buds 

 so that it is quite impossible to reach them. When the older plants, par- 

 ticularly cyclamen, have become badly infested it usually will be advis- 

 able to bum them and sterilize the soil, but the grower should avoid get- 

 ting his plants in this condition by exercising preventive measures when 

 the plants are young. 



Dusting the plants with sulphur dust or tobacco dust when the plants 

 are heavily infested is of very little avail. Dipping the plants in an oil 

 emulsion called Yel-ros, which contains a good deal of xylol, a very pene- 

 trating oil, helped some, and no doubt will free the later blooming plants 

 for Easter. This was demonstrated on some of the infested plants in the 

 Experiment Station greenhouses. This oil emulsion was tried out in the 

 greenhouse at the rate of i to 40, with the result that very little burning 

 resulted, and no doubt it may be used weaker. A number of plants 

 which were retained came out in good shape. The Yel-ros is too severe 

 a spray for the young plants, however, as a considerable amount of burn- 

 ing resulted. 



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