v HETEROMERA CANTHARIDAE 269 



access is gained to the cells the little Metoecus pierces the skin of 

 one of the wasp-grubs, and entering in it feeds on the interior : 

 after it has increased in size it emerges, changes its skin, and 

 assumes a different form and habits ; subsequently, as an external 

 parasite, entirely devouring the wasp-larva, and then becoming a 

 pupa, and finally a perfect Metoecus, in the cell of the wasp. The 

 wasps, though they investigate the cells, do not apparently entertain 

 any objection to the Metoecus, though there may be sometimes as 

 many as twenty or thirty of the destroyers in a single nest. A 

 few hours after the Metoecus has become a winged Insect and has 

 escaped from the cells, it appears however, from the observations 

 of Erne l on nests of wasps in captivity, that the wasps become 

 hostile to the foreigners, and it is probable that in a state of 

 nature these leave the nest as quickly as possible. Emenadia 

 flabellata, a genus allied to Metoecus, has been discovered by 

 Chobaut to have a similar life-history, except that it attacks a 

 solitary wasp of the genus Odynerus? An old record to the 

 effect that a second species of Emenadia, E. bimaculata, lives in 

 the stalks of Eryngium carnpestre, on the pith, is now thought to 

 be erroneous. Fabre has found the larvae and pupae of another 

 Ehipiphorid in the cells of a bee, Halictus sexcinctus. 



The most remarkable of the Ehipiphorids, from the point of 

 view of its habits, is certainly Symbius blattarum, which is now 

 treated as the same as an Insect previously described by Thunberg 

 from specimens found in amber and called Ripidius pectinicornis. 

 This species is parasitic in cockroaches ; the male and female are 

 very different, the former being an active winged Insect, while 

 the female is worm-like, differing but little from the larva, and 

 never leaving the body of the cockroach. It is to be regretted 

 that the life-history is not better known. The species has been 

 found on board ship in vessels coming from India ; the male has 

 been met with in several European countries, but the female is 

 excessively rare. 



Fam. 75. Cantharidae or Meloidae (Blister-beetles, Oil-beetles}. 

 Head with an abrupt neck ; elytra and sides of the abdomen with- 

 out any coadaptation ; each claiv of the feet with a long appendage 

 closely applied beneath it. This distinct family consists of 

 Heteromera with soft integument, and is remarkable for the fact 

 that many of its members contain a substance that when extracted 

 1 Mitt. Schweiz. ent. Ges. iv. 1876, p. 556. - Ann. Soc. ent. France, Ix. 1891, p. 447. 



