158 WASPS [CH. V 



the researches of Dr TV A. Chapman 1 the life history 

 of this form is now fairly well known. It is almost 

 certain, though not actually proved, that the eggs are 

 laid in cavities in dead wood, posts, palings and so forth, 

 during the autumn. Active hexapodous larvae emerge 

 from the eggs next spring and by some means find their 

 way into the nests of wasps. On the analogy of what is 

 known to occur in the case of the oil-beetle Meloe, it is 

 highly probable that the young larvae attach themselves 

 to wasps while these are engaged in gathering "wasp- 

 paper" from the surface of the timber, and are thus 

 conveyed within the nest. The larva is black, about 

 0*5 mm. long, and it possesses a sucker upon the end of 

 the abdomen. By means of this organ it is able to stand 

 erect and paw the air with its feet as though groping for 

 some object. Arrived at its destination the larva eats its 

 way into a wasp-grub and, feeding on the tissues of its 

 host, attains a length of 4'5 mm. It now emerges through 

 the ventral surface of the fourth segment of the wasp- 

 grub and casts a skin which plugs the wound so caused. 

 By this refinement its victim is saved from immediate 

 death and reserved for the full benefit of the Rhipiphorus. 

 The larva next seizes the wasp-grub by the second segment 

 and becomes an external parasite upon it. When about 

 6 mm. long it casts another skin which remains between 

 it and the wasp-grub, the two creatures being now 

 vis-ci-vis. Eventually the wasp-grub is entirely con- 

 sumed, but not before it has spun its cocoon within 

 which the Rhipipliorus completes its own metamorphosis. 

 1 Ann. Mag. Nat. Hist. 1870 and Ent. Month. Mag. (2) xxvu. 1891. 



