28 CATERPILLARS AND THEIR MOTHS 



plainly unless the scales are removed. The abdominal 

 spiracles are protected by the scales, but often may be 

 seen clearly, two on each segment. The last segment 

 has the ovipositor of the female, or the claspers and 

 intromittent organ of the male. The claspers are 

 horny plates with which the male holds the abdomen 

 of the female while mating. The intromittent organ, 

 or ejaculatory duct, conveys the seminal fluid of the 

 male into the pouch of the female. 



Some species of moths have the power of thrusting 

 out tufts of bristles which give an odor. In some 

 cases the odor is disagreeable to birds, mice, and bats, 

 and serves to protect the moth from thoir attacks. In 

 other cases the males only possess scent-tufts, and 

 emit an odor which is thought to be attractive to the 

 females. In some species the tufts are on one pair of 

 the legs, in others on the abdomen and are concealed 

 when not in use. Some species have on the wings 

 large scent-glands under the scales, others protrude 

 long filaments which give out the odor. 



In many species the male and female differ in color 

 or marks and may be distinguished at a glance. In 

 others the width of the antenna and size of the abdo- 

 men are distinguishing marks, the wider or more 

 pectinate antennae showing the male, while the much 

 larger abdomen shows the female. In other cases the 

 different forms of the frenulum will tell the sex, while 

 the claspers always show the male. In entomological 

 writings the sign ? is used to indicate the female, and 

 6 to indicate the male. 



