190 IOWA ACADEMY OF SCIENCE Vol. XXV, 1918 



case of the house spider may be cannibalistic appears very prob- 

 able, yet in regard to this point we have no direct evidence. 



The female of the house spider, especially when kept in cap- 

 tivity, is liable to slay her mate. In nature this apparently 

 seldom happens, due, as the writer's observations appear to show, 

 to the elusiveness of the male. It is seldom indeed that, in nat- 

 ural conditions, the male is found slain in the snare of the female. 

 The ^\Titer has records of several males benig slain by their 

 mates in captivity. Having no chance of escape they were 

 caught by the angiy females and in all such cases were eaten as 

 prey. 



The death rate among the little spiderlings after they have 

 emerged is surprisingly great. From a brood of a hundred or 

 more rarely more than two or three will reach maturity. In 

 nature this would probably be explained on account of natural 

 enemies, of which there are many. Yet even when tliey are 

 carefully guarded in breeding cages it is found impossible to 

 rear to maturity more than a very small percentage of the spider- 

 lings coming from the cocoons. Even the separation of the 

 young into individual cages appeared to lessen the difficulties 

 but little. 



Never has the writer observed one of these free living spider- 

 lings to snare or kill another, although he has very strong evi- 

 dence of one spiderling killing two others. This spiderling was 

 found feeding on one of its brothers, and the next day the body 

 of the other brother was found sucked. It may be that both of 

 the individuals fed upon had died of natural causes, hence we 

 have no convincing evidence of cannibalism in this case. Can- 

 nibalism, if it does exist among the emerged spiderlings, is so 

 rare that it should not be considered as a part of the normal 

 behavior of the species. 



HABITS OF THE MALE. 



The male is not nearly so often observed as the female. Three 

 reasons may be given for this ; he is much smaller, for much of 

 liis life he is a wanderer, and lastly he is much shorter lived 

 than the female. 



The male (iigure 37), although varying considerably in colora- 

 tion, is much darker than the female. The prevailing color is a 

 light chestnut brown. The legs do not as a rule appear banded 

 as in the female, and the abdomen is not so mottled. As is 



