October, '12] ewing: habits OT CHEYLETUS 419 



beyond the tip of the abdomen. Total length of body excluding the beak, 0.58 mm.; 

 width, .025mm. 



Habits 



The Molting Process. I was unable to observe the actual process 

 of molting, but an examination of thie cast skins showed that they had 

 been split transversely at or near the scapular groove. This rupture 

 was sometimes complete, and the two parts of the old skin when cast 

 remained separated from each other some distance. The process 

 evidently is the same for all stages. In some instances the posterior 

 part of the cast skin showed a lateral rupture passing backward from 

 the transverse one. 



Nature of Food. This species is entirely carnivorous in its diet, 

 and much prefers to catch its prey. Young individuals prefer to live 

 upon the eggs of other mites if they can obtain them, and individuals 

 of all stages will suck the juices of freshly killed creatures if they are 

 unable to catch live ones. 



Method of Approach and Attack upon Prey. These predaceous mites 

 are extremely cautious about attacking creatures even smaller than 

 themselves. I have watched the process several times upon the stage 

 of the microscope. An individual will first approach its suspected 

 prey slowly and touch it wath the long tactile hairs on its front legs. 

 Then it vnW retreat. Again it will repeat the process from another 

 direction and again retreat. Now the hind legs will be presented to 

 the victim and again a retreat will be made. When several of these 

 actions have been performed and apparently if the Cheyletus has 

 decided that it has prey and not a dangerous enemy, it rushes upon 

 the latter and seizes it at the nearest point of attack by means of its 

 powerful palpi, inserts the beak, and begins to suck the juices. 



The Feeding Process. The victims do not stop movement when 

 seized by this mite, as is claimed to be true by some ^Titers for species 

 of Cheyletus; in fact, frequently they are not killed at all. If the 

 Cheyletus has been fasting it will seize its victim and suck it dry. I 

 observed one under such conditions, and it took just 13 minutes for 

 the feeding process. 



After the beak is inserted one can see the strong pharyngeal muscles 

 contract and relax very rapidly, while the stomach and abdomen 

 gradually become distended with the blood sucked from the victim. 



Number of Victims Killed. The adult individuals of Cheyletus 

 seminivorus will frequently attack and kill many of their victims and 

 suck but little of the blood. When they are very hungry they suck 

 their victims dry, but if plenty of food is at hand they do not suck them 



