RHJPIPHORHLE. 



1G9 



wrong to treat thein as distinct. The insects belonging to the 

 parasitic sections have exceedingly interesting life-histories, which 

 are as yet only partially known. The most familiar is Metoecus 

 paradoxus, which is parasitic on wasps. The greater part of its 

 history has been worked out by Dr. Algernon Chapman (Ann. 

 Mag. N. H. (4) vi, 1870, p. 314, and Ent. Mo. Mag. 1891, p. 18). 

 The young larva appears to be similar to that of the campodeiform 

 larvse of the MeloYdvE; it is a little black hexapod, about 1 mm. 

 in length, broadest about the fourth segment and tapering to a 

 point behind; the tibiae end in two or three claws (biungulin or 

 triungulin), which support and are obscured by a large transparent 



pulvillus or sucker of about twice their length ; che last segment 

 is terminated by a large double sucker similar to those of the 

 legs. How the young larva enters the wasps' nest is not quite 

 known, but Dr. Chapman has found the eggs in dead wood and 

 thinks it probable that they are carried by the wasps to their 

 nests in the wood shavings which they use for their construction. 

 It seems more probable, however, that the active larvse hatch out 

 and attach themselves to the wasp while it is gathering this 

 wood *. At any rate the young larva finds its way into a cell 

 containing a wasp larva and immediately attacks it and penetrates 

 into its interior ; after feeding within the larva and increasing 

 largely in size it quits the host, changes its skin, and then becomes 

 shorter and thicker, At this stage it is found lying like a 

 collar under the head of the wasp-grub, whose juices it goes on 

 devouring ; it then again changes its skin, devours the whole 

 remainder of the grub, changes to a pupa, and a few days after- 

 wards emerges as a perfect insect. The full-grown larva is very 



* A fact against this is that no wasps have been found infested with these 

 larvae, as are the Andrence with the young Meloe larvaj ; at the same time I 

 believe that the larva and not the egg must be carried to the nest. Dr. 

 Chapman takes strong exception to my theory (Brit. Col. v, p. 81) that the 

 egg is laid in the cells. 



Fig. 73. — Emenadia ferruginea ; female. 

 Head and prothorax of male. Antenna of male. 



