54 



AMERICAN SPIDERS AND THEIR SPINNINGWORK. 



blunt head of the larva was too large to make an attachment. When full 

 fed the larva was about three-eiglitlis of an inch long, and had fourteen 

 segments, counting the head as one. The cocoon was shuttle shaped, 

 whitish and thin, the spider's original web forming its suspending cords ; 

 the movements of the larva and pupa were perceptible through the cocoon. 

 The perfect fly aj^peared on the 12th of June, and proved to be a female 

 of Polysphincta tuberosa Gravenhorst. 



VII. 



Mr. John L. Curtis, ^ of Oakland, California, has written me an inter- 

 esting account of a new body parasite taken upon a species of Theridioid 



spider, Labulla inconstans.'^ 



The siiider is quite 

 Body Par- '■ . ^, 



asit common in the re- 



gion surrounding 

 San Francisco, and domiciles 

 ^3- in large leaves, the edges and 

 ends of which it bends downward, and 

 fastens with a sheet of web composed of 

 many white threads spun across from side 

 to side. The cocoon, which is round and 

 white, is woven within this maze, and is 

 jealously watched by the mother, a small 

 spider of a light gray color, with pinkish 

 tints on the legs and a tinge of yellow on 

 tlie abdomen. 



On July 13th (1890) a specimen was 

 found upon whose abdomen was fixed a 

 large yellow larva. By the 15th the larva had entirely consumed the spider 

 and spun itself into its cocoon. (Figs. 41, 42, 43.) On the 17th it clianged 

 to chrysalis, and on the 27th of the month hatched. The cocoon is a cylin- 

 drical case of loose fibres, and liung suspended, head downward, upon lines 

 stretched within the bottle wherein it was bred. Mr. E. T. Cresson, of Phila- 

 delphia, has identified the parasite insect thus hatched as a probably new 

 species of Polysphincta, a genus of Pimplinai, a subfamily of the great 

 family Ichneumonidaj. It is obvious that in order to deposit her egg upon 

 the body of the spider, this mother Ichneumonid must have successfully 

 threaded the labyrinth of intercrossed lines and obtained a fa\-orable posi- 

 tion underneath the abdomen. A delicate piece of aranead scouting this! 



12. 

 Fig. 41. Parasite cocoon in site, natural size. 

 Fig. 42. The same, enlarged greatly. Fig 

 43. The pupa. 



' I regret to record the death of this iiroiuisinj; young naturalist since writing this note. 

 Though an incurable invalid he was an enthusiastic lover of araneology, and had already 

 done some good work therein. 



^ Dr. George Marx thus determines the genus, and the specific oanie is that suggested 

 by Mr. Curtis. 



