EXTERNAL PARASITES OF SPIDERS. 178 



Theridion which carried a maggot on the back of its abdomen. 

 This larva was then about three millimetres long, but by the 

 next day it had doubled in size and was shining white, with red 

 spots, the victim spider lying dead on the earth ; the larva then 

 gradually became whiter in colour, and on the 27th spun a thin, 

 transparent, white, oblong cocoon, and later turned to a yellowish 

 pupa therein. On August iJth— only fourteen days after the 

 death of the spider — a male Polyspldncta hoops, Tschek,, emerged 

 (Deutsche Ent. Zeit., xxi., 285). 



In ' The Fauna of Devon : Ichneumonidfe " (7'rans. Devons. 

 Ass. Advanc. Science, &c., 1881) Mr. Edward Parfitt tells us 

 that he had bred Acrodactyla degener, Haliday, from "a reddish 

 larva, found feeding on a small spider. The bod}' of the spider 

 was not large enough to contain the larva, so that part of it was 

 exposed. The spider lived until the larva was ready to undergo 

 its change into pupa. It then spvni a cocoon, fusiform and 

 angular, attached at both ends to the glass cover of the box after 

 the manner of a hammock. It remained in pupa about a 

 fortnight, and came out September 19th, 1871" {I.e., pp. 41, 42). 



Ichneumon parasites of spiders' eggs are numerous, and many 

 species have been bred from various spiders' nests, especially 

 from the elegant little nests of Agelena hrunnea ; but it is not to 

 these I now allude ; it is to the interesting cases of external 

 parasitism on the adult spiders. Notwithstanding all the above- 

 mentioned published information, very little appears to be 

 generally known on the subject; I am therefore glad to be in the 

 position to bring forward two more instances from well known 

 observers, and to be able to give a good figure of a Polysphincta 

 larva from a drawing made by Mr. Gr. C. Bignell. The species of 

 the genus Polysphincta and Haliday's closely allied Acrodactyla 

 all appear to be rare in Britain. The}' are probably exclusively 

 spider vampires, as Boie terms it, although Brischke gives JP. 

 carhonator as bred from a sawfly {Xematiis ventricosus), but this 

 is probably an error ; both P. rujipes and P. hoops he gives as 

 bred from Epeira diademata. Ratzeburg gives many hosts, but 

 the information and determination is somewhat doubtful. 



The Rev. A. Matthews, of Gumley, thus writes : — "On July 

 4th, 1874, my brother, the Rev. H. Matthews, found a spider with 

 a white maggot-shaped larva lying across its back, between the 

 thorax and abdomen, firmly attached by each extremity of its 

 body to the under side of the spider's thorax, between the 



