NESTING HABITS AND PROTECTIVE ARCHITECTURE. 311 



brood will occupy the abandoned snare of an adult Orb weaver, and, clear- 

 ing out the space between the radii, spin their own minute orbs. I have 

 seen a brood of young Epeira patagiata attempt this sort of squatting 

 upon the premises of an adult Zilla x-notata, very much to their own dis- 

 comfort. For, although the little fellows succeeded in getting positions for 

 their minute orbs, the original proprietor, by skillful management, was 

 able to dislodge and one after another devour them, until she had eaten 

 up nearly all her guests. 



Moreover, among certain species of the Retitelarise, the habit has be- 

 come fixed of invading the snares of other species for the purpose of 

 destroying the occupants. Argyrodes trigonum, for example, will 



T , invade the nest of the Labyrinth spider, whose maze forms an 

 Invaders. ./ i j 



admirable retreat, and therein will establish herself. Another 

 species of Argyrodes, which I have described as A. piratica, was sent to me 

 from California, and is said by Mrs. Rosa Smith Eigenmann to be an 

 habitual depredator upon the premises of the Orbweavers of San Diego. 

 The little creature will fearlessly invade the snare ; attack, destroy, and de- 

 vour her huge opponent. The particulars of this habit I reserve for the 

 chapter (Vol. II.) upon the Enemies of Spiders. 



The abandoned nest of Orbweavers is often occupied by Tubeweaving 

 spiders. Agalena noevia especially finds it a pleasant retreat, and makes 

 it the centre of her broad, sheeted snare. So also I have found the 

 rolled leaf nest of a young Epeiroid occupied by a Saltigrade. I have 

 no evidence, however, that any of these spiders deliberately dislodges the 

 owner in order thus to take possession. Nor have I ever seen one Orb- 

 weaver make a raid upon the premises of a congener for a like purpose. 



Mrs. Treat records ^ a case which looks very much like nest parasitism. 

 An interesting Lycosid, Dolomedes scriptus, appeared to take a special fancy 

 for the nest of a female Shamrock spider. For more than two weeks, 

 while the Doloniede was carrying her cocoon, her favorite resting place was 

 on the top of the Orb weaver's tent, and often, when the latter left her 

 domicile to seek prey upon her orb, as is her custom, Dolomede would 

 stealthily sli}) inside. But she always seemed to know when Trifolium 

 was about to return, and would quickly emerge and take her place on the 

 outside. The only wonder to me, in this case, is that the Lycosid, which 

 is a large and powerful spider, abundantly able to cope with and destroy 

 Trifolium, did not at once make a meal of the Orb weaver whose home 

 she coveted, and, after the fashion of human creatures, take possession of 

 the premises from which she had dislodged the rightful occupant. 



On the whole, I am inclined to think, although the facts are cer- 

 tainly inadequate to form a just conclusion of any sort, that cases of 

 proper nest parasitism are rare. That is to say, it is not often that one 



1 " My Garden Pets," page 24. 



