n6 



THE QUARTERLY REVIEW OF BIOLOGY 



assumed that the unusual prolongation of 

 the life of this male is due to the regular 

 and abundant food supply furnished during 

 the last four years of his life. 



Soon after the mating season the males 

 begin gradually to fail. The abdomen 

 begins to shrink slowly, and the spider 

 gets more and more sluggish. Finally 

 the abdomen is nothing more than a 

 shrivelled and deeply wrinkled prolonga- 

 tion of the cephalothorax, yet the male 

 with the legs drawn up close to the body 

 will live on for several days or even a 

 week. It seems an excellent picture of 

 death due to old age, a gradual and 

 complete exhaustion of all the sources of 

 energy. 



The females present a very different 

 picture. At the age of eleven they are 

 probably not even mature. Records, as 

 yet not quite complete, show that the 

 females become sexually mature when 

 twelve or thirteen years of age. One 

 female that was brought into the labora- 

 tory when fully matured, fourteen to 

 sixteen years old, is now, nine years later, 

 still in a very healthy and vigorous 

 condition. 



The tarantula, Eurypelma californica, 

 common in a number of the southwestern 



states, has been under observation for! 

 about nine years, with the result that the : 

 life cycle and the mating habits of the? 

 male are fairly definitely known. The 

 life cycle from hatching till sexual ma- 

 turity is about eleven years, with the 

 possible variation of one year more or one 

 year less. During this time, a male 

 undergoes about twenty-two molts. 

 Until the last molt the male is indis- 

 tinguishable from the female. 



As many as four sperm webs are made 

 by one male, indicating that he will mate 

 at least four times. In the preparation 

 for mating the stimulation of the sex 

 glands is so thorough and deliberate that 

 it seems strange for so low a form of ani- 

 mal life. Mating has been observed 

 ten to twelve times. 



After the mating season the males soon 

 decline in vigor. Shrinking and becom- 

 ing more and more sluggish for some 

 time, they die apparently as a result 

 of a total exhaustion of all sources of 

 energy. 



The females, judging by records not 

 quite complete, become mature when 

 twelve or thirteen years old. After at- 

 taining maturity, they will live for a num- 

 ber of years; it is not known how many, 

 but certainly till they are twenty years 

 old and probably much older. 



LIST OF LITERATURE 





Baerg, W. J. 1911. Regarding the habits of 

 tarantulas and the effects of their poison. Scien- 

 tific Monthly, vol. xiv, no. 5, pp. 481-489, 

 4 figs. 



. 1916. Regeneration of appendages in the 



tarantula, Eurypelma californica. Annals Ent. 

 Soc. America, vol. xix, no. 4, pp. 511-513. 



Bolsche, Wilhelm. 1917. Das Liebesleben in der 

 Natur. ErsterTeil, pp. 356-369. 



Brazil, Vital. 1916. Contribucao ao estudo do 

 veneno das Aranhas. In Memorias do Instituto 



do Butantan, Tomo III, Fasciculo Unico, pp. 



34-41, pis. 18-10. 

 Ewing, H. E. 1918. The life and behavior of the 



house spider. Iowa Academy of Science Proc, 



vol. xxv, pp. 177-104, 11 figs. 

 Petrunkevitch, Alexander. 1911. Sense of sight, 



courtship and mating in Dugesiellahent^i (Girard) 



a Theraphosid spider from Texas. Zool. Jahrb. 



Abt. f. Syst. Geog. und Biol. d. Tiere, Bd. Ill, 



PP- 355^375. pls.io-n, 4 figs. 



