THE HOUSE SPIDER 199 



The body of the second nymph is an obscnre yellowish green, 

 with dark markings above similar to those of the adult. The 

 eephalothorax is lighter than the abdoinen. The eyes are 'black 

 and eonspiciious. The legs are white marked with dark bands. 



The Third Nymph. — The third nymphal instar is similar in 

 practically all respects except size to the second instar.' It is 

 quite active, and spins better and snares better than the second 

 nymph. 



Data were obtained on the length of the third nymphal stage 

 for eight individuals. The minimum time for this stage was 6 

 days, the maximum 20 days. The average for the eight indi- 

 viduals was 12 days. This is almost exactly one-half the time 

 consumed in the second stage, and this difference can probably 

 be partly explained by the fact that prey can be much better 

 snared in this stage, hence the nymphs are better nourished. 



The Fourth Nyynph. — The fourth nymph iS like the third only 

 tliat it is larger and stronger. The average length of the fourth 

 nymphal stage was found to be 10.2 days. Five individuals 

 were used in ol)taining this average. The shortest time observed 

 was 6 days, the longest 21 days. 



That there is considerable danger attendant to the molting 

 process of the spiderlings as well as of adults is evidenced by 

 the fact that one of these fourth nymphs was observed to die 

 cluring the process of casting off the third nymphal skin. The 

 skin of the eephalothorax came free above, Init the spiderling 

 M'as unable to withdraw its legs from their old skins. 



The Fifth Nymph. — The fifth instar has no special distin- 

 giiishing characteristics. The length of this stage was noted in 

 the case of two individuals. One passed through this stage in 

 5 days, the other in 9 days. 



One day the writer dropped a fly upon the web of a fifth 

 nymph. The nymph immediately dropped to the bottom of the 

 cage feigning death. Here it remained motionless for a long 

 time. This is a habit frequently noticed in adults. Only fear 

 appears to bring about the response. 



It sometimes happens that there is no fifth nymphal stage in 

 the case of female individuals. At least the writer has one 

 record of a female reaching maturity with the fifth molt. In 

 another case it was found that the specialized sexual structures 

 of tlie palpi of the male appeared during the fifth stage. 



