THE MITES 33 



D. Compare specimens of young female ticks with specimens 

 that are fully engorged. 



E. Examine again a series of males and females of several 

 species, to determine sexual differences. 



EXERCISE 19a 



I 



THE MITES 



CLASS ARACHNIDA, ORDER ACARINA, FAMILY GAMASIH 



A. General characteristics of mites; usually quite small, just 

 about visible to the naked eye, some larger. The body portions 

 are more or less closely united. The mouthparts are piercing 

 and sucking structures. The four pairs of legs are generally 

 well developed, terminating in suckers. The sexes are separate. 

 The young are hexapod. 



B. Characteristics of Gamasidce; the legs are six-segmented and 

 terminate in a pair of ungues and a sucker-like disc. The 

 stigmata or breathing pores are located between the third and 

 fourth pairs of legs. 



C. The poultry mite, Dermannyssus gallina. Study speci- 

 mens mounted in balsam. 



a. Measure size of the specimens. How do the males and fe- 

 males differ in this respect? 



b. Note the position of the legs with respect to the body 

 divisions. 



c. Count the segments of a leg and note the terminal struc- 

 tures. 



d. Locate the stigmata. 



Draw the specimen, labelling the parts. 



