106 Biology of Necrobia ruficollis 



(v) Killing and eating fly-maggots. As stated above, in none of my 

 experiments in 1917 could the A^ecfo&m-larvae be induced to attack 

 living maggots of any age. But early in 1918 Mr R. E. Tooke watched 

 them in the act. His observations may be recorded in his own words: 



" Several larvae were placed in a receptacle containing sawdust and 

 were left for about 24 hours without food. Two fly-larvae were then 

 placed in the receptacle. For some time, although the iVecro?na- larvae 

 frequently came into contact with the fly-larvae they did nothmg more 

 than open their mandibles, more as a defensive than an offensive action. 

 It was not until one of the fly-larvae crawled over a iVecro6m-larva, that 

 there was any definite attempt on the part of the latter to seize the 

 fly-larva. Even then it seemed to be an act of defence rather than of 

 aggression. In the resulting struggle the iVecro6m- larva hung on tena- 

 ciously; eventually the skin of the fly-larva was ruptured and it became 

 quiescent, and the iVecro6^'a-larva commenced eating it. The soft parts 

 were eaten out leaving the empty skin. The other larvae of the beetle 

 also took part in eating the dead maggot, even though the second maggot 

 was still actively moving about the vessel. This maggot was ultimately 

 killed and eaten in the same way as was the first. Live maggots placed 

 with other iVecro&m-larvae were also killed and eaten. N ecrohia-lwyde, 

 were often seen to attempt to seize mites, but seemingly without success." 

 Pupation. Heeger(8) speaks of the " unverhiillte Verwandlung zur 

 Puppe." In one experiment, certainly, two of my larvae did pupate 

 fully exposed, lying on their backs, on the sawdust in a small vessel: 

 but these had probably been subjected to unfavourable conditions, 

 having refused several kinds of food offered to them. Normally the larvae 

 either make a cell and line it with a hardened, opaque, white secretion, 

 or make use of some existing cavity — notably the interior of a fly- 

 puparium — screening all openings over with the white secretion. 



The very frequent use of empty puparia of flies has been discussed 

 by several writers (Perris, Gallois, Tascheiiberg, Kemner [p. 200]). I 

 found this to be quite the favourite place for pupation, puparia of 

 Calliphora, Phormia coerulea, and Musca domestica all being used. In 

 the case observed by Gallois the puparia were those of Lucilia, while 

 in that recorded by Taschenberg the fly is said to have been Calliphora 

 azurea. Fallen^. The end of the puparium where the fly has emerged is 



^ Protocaliijt/ioru (or Avihoajnta) azurea (Fallen) is a rather scarce fly, the larvae of 

 which have been found infesting nestling birds. Probably what is really meant is Phormia 

 coerulea, R.-D., frequently but less correctly referred to as Protocalliphora groenlandica, 

 Zett., a species which often Ineeds in profusion in bone factories and other places where 

 dead animal matter accumulates. 



