ENEMIES AND THEIR INFLUENCE. 393 



ichneumonid larva oiie-lialf inch long. Tlie spirit bath had evidently dis- 

 turbed tlie creature when near the period of emerging, and being affected 



by it, it at once cut a way through the skin of its host, and 

 Parasites wriggled out of the body into the alcohol, where, of course, it was 

 the Bodv "^l^s^^^'oyed. The site of this larva upon its host corresponded 



closely with that of the parasitic guest described by Blackwall, 

 on the upper part of the abdomen. In size the two larvse are nearly equal, 

 and they proljably belong to at least the same genus. 



Menge has added to our knowledge of the parasites infesting spiders, 

 and I present a brief abstract of his observations.' Micriphantes, The- 



ridium, Bolyphantes, and other sjiecies found crawling on the 

 p -^ ground are infested with a cinnabar red species of Dermanyssa. 



But one of these is usually found on an individual, seldom two, 

 and hardly ever three. It is fatal to tlie smaller varieties alone, and only 

 infests the larger varieties while youug. He found Mermis allicans on a 

 Water spider (Argyroneta aquatica), and saw it escape from the body and 

 tumble about in the water. During the latter part of June he took a fe- 

 male of Clubiona putris within its little silken sac on a stem of heath, and 

 confined it for observation. A week thereafter it had disappeared, while 

 within the sac, on a few horizontal threads suspended in the centre, lay 

 a yellowish white pupa about five millimetres long, which had eaten the 

 spider except the legs and a small part of the skin. In another week a 

 winged insect, probably Henops marginatus or Oncodes pallipes, emerged 

 from the pupa. During the brief adult life of this insect it takes no 

 nourishment, but soon finds its mate and deposits its eggs upon the spider. 

 Immediately after hatching, the maggot makes its way into its host's body, 

 l)roVjably through the rima prudendi. 



The same author describes two other parasitic larv» which he failed 

 to bring to maturity, but which probably also belong to the Hymenoptera. 



The first was found August '27th, upon the posterior part of a 



, full grown female Arctosa cinerea, taken in the sand under 



Larvae. '^ 



fallen leaves; it was naked, reddish white, without feet, two mil- 

 limetres long. It astonished the observer to note that the large spider re- 

 mained perfectly quiet while the larva nibbled its way into the body, 

 when a movement with the legs would have removed it. On the second 

 day the spider was quite dead, and the larva was then four millimetres 

 long. Eight days thereafter the larva had devoured the entire abdomen, 

 the inner cephalothorax, and the thigh of one hind leg ; it had increased 

 about one-half in size, had satisfied its hunger, but was very uneasy. It 

 was placed in sand to mature, and there overspun itself, but never further 

 developed. 



Another larva was found, July 28th, on an immature male of Miranda 



' Menge, Preussische Spinnen, under Parasites of the Spider. 



