( xli ) 



served the Carder Bee Bombus derha melius, Kirb., cooling 

 its larvae in this way when the nest had been opened and they 

 were exposed to the direct rays of the sun. 



W. A. Lamborn's observations on the method by 

 WHICH Tachinid flies escape from the mud cells of 

 EuMENES. — Prof. Poulton read the following record of 

 observations, received from Mr. W. A. Lamborn : — 



" No. 517. A five-celled nest of Eumenes maxillosa, de 

 Geer, was found on 26th March, 1914, built on to the wall of 

 a cement tank, but was unavoidably broken in removal. 

 One cell newly constructed and unsealed contained two green 

 Noctuid larvae, both of the same species (at bottom of tube 

 now sent), and a sausage-shaped ovum dangled from the 

 roof. Another sealed cell contained a half-grown wasp grub 

 and six Noctuid larvae, of at least two species, and different 

 from those in the unclosed cell. Two of these had been partly 

 consumed by the grub. The third cell contained a full-grown 

 grub, and in the two remaining cells were Tachinidae, pupae 

 in the one and pupae and one imago in the other. 



" The discovery of this Tachinid imago gave me the 

 opportunity of carrying out an investigation into the means 

 by which the flies succeed in making their way through a 

 stout mud wall into the outer world. The Tachinid pupae 

 were placed in two old cells made by a wasp of the same species, 

 and these were gummed on the inner side of the glass lid of 

 a box, the edge having been previously rubbed down so that 

 there was no possible hole of egress. In this way it was 

 possible to observe every movement of the contained insects. 



" On 27th March, at 7 a.m., it was seen that the flies were 

 beginning to emerge and soon all were running about aimlessly 

 over one another, stopping occasionally and then pufiing the 

 ptilinum in and out. Each act of distension of the ptilinum 

 was accompanied by contraction and elongation of the 

 abdomen, which was so tumid as to stretch the intersegmental 

 tissues. The ptilinum itself was dilated to an extraordinary 

 degree, for it was protruded in advance of the head for at 

 least double its normal anteroposterior diameter, and, when 

 thus fully protruded, an expansion from side to side in front 

 of the eye took place, accompanied by an outward rotation 



