386 Journal of Agricultural Research voi. x, no. s 



In the female quiescent stage the clavate organs between the first and 

 second pair of legs were plainly seen. 



After a few days, during which there are the various internal changes, 

 the molting process begins. The body moves in a series of twists and 

 turns, when suddenly the old skin splits traversely along the cephalo- 

 thoracic abdominal groove, and finally the adult mite emerges. 



The length of the quiescent, or resting, stage varies somewhat, but 

 the average of lo specimens taken from the active larv^se through to 

 molting was 3K days. This would give the average for the entire length 

 of the larval stage approximately 10 to 11 days. 



HABITS OF THE ADULTS 



The adults may be found at any time on the plants from November 

 until late spring and no doubt may be found in the greenhouse all the 

 year round. The males are comparatively short-lived, the females 

 living longer. During the middle of January, 191 7, more males were 

 to be found than at any other time. The females seem more abundant 

 during the fall and winter, when most of the damage to the plants occurs. 

 It is almost impossible to get a clue to the number of generations by 

 making observations in the greenhouse, since they overlap so com- 

 pletely. After the first generation, if the mites are at all abundant, 

 eggs, larvae, and adults no doubt may be found in the greenhouse 

 simultaneously throughout the remainder of the year. During a portion 

 of the year it is thought the mites become less numerous until there is 

 no evidence of their presence when their food plants are not present; 

 possibly the females semihibernate. 



From the data at hand it is apparently true that the mites appear in 

 early June in the greenhouse on the young plants from seed of the previous 

 August, and produce generation after generation on the plants until the 

 last of March, and no doubt longer the succeeding year. The mites then 

 gradually become less abundant, again to appear later in the summer, 

 being held over apparently by the semihibernating females in the soil 

 scattered in the greenhouse. 



This has been demonstrated somewhat on plants in the laboratory. 

 The foliage was cut from the corms completely and allowed to dry out 

 a little so that no growth was to be seen on the corms. These plants 

 were left in this condition for several months and then watered thor- 

 oughly, and the foliage was allowed to grow. On previous observation 

 only females could be found about the corms and in the soil before the 

 foliage started. In a very short while the foliage was seen to be curling, 

 and numerous adult mites were present. 



REARING METHODS 



Several sorts of rearing cages were tried in the work, but it was found 

 that the use of but one gave the best results. The potted cyclamen 

 plants were kept at first next to the window in the laboratory where 



