1924 ENTOMOLOGICAL SOCIETY 63 



Silver Fish (Lepisma domestica and L. saccharina) . In bakeshops the 

 former of these two insects is very common ; in fact, it is claimed by some bakers 

 that practically every bakeshop is more or less infested. The other species is 

 found here and there in private homes, but is not yet very common. 



Horn Fly (Hoematobia irritans). In Middlesex and Elgin, horn flies seemed 

 to be exceptionally abundant this summer. 



Heel Fly (Hypoderma bovis). More trouble was reported from cattle 

 gadding as a result of the attacks of this warble fly this year than last. 



A STUDY OF THE PUPAL CASE OF PRIONOXYSTUS MACMURTREL 



C. B. Hutchings, Entomological Branch, Department 

 of Agriculture, Ottawa. 



Prionoxystus macmurtrei Guer-Men., commonly known as the Lesser 

 Carpenter Worm, is a serious enemy of the red oak in parts of Eastern Canada. 

 The larva makes large winding tunnels in the wood and requires three seasons 

 to mature. 



Pupation takes place, usually, in the fall of the year within a silk-lined 

 cell at the further end of the tunnel. The pupa is dark, mahogany-coloured 

 and shining. The average female case is 45.5 mm. long and 10.8 mm. wide; 

 the male being 24.5 mm. long and 6.0 mm. wide. 



About the last few days in May or early in June, the pupa leaves its chamber 

 and begins to move forward on its back into the tunnel. By a number of con- 

 tractions and expansions of the abdomen, it makes its way along the passage 

 to the mouth of the burrow, where it projects itself sufficiently to the exterior 

 to expose the head, thorax and one or two segments of the abdomen. The 

 remainder of the case rests within the tunnel walls, anchored there securely 

 by means of the numerous spine-like processes which appear on the abdomen. 

 A few violent pulsations and the head shell splits open, allowing the moth to 

 gain its freedom. 



The following is a study of the principal features of the external morphology 

 of the case. 



The Head 



Vertex. The vertex is represented by a narrow chitinous band which is 

 not clearly visible before dehiscence. 



Front. Dorsally, the front bears two conspicuous setae which are set in* 

 slight depressions near the epicranial suture ; ventrally, four indistinct punctures 

 arranged in an irregular row. 



Gence. The genae are probably represented only by a slight rugosity 

 near the fronto-clypeal suture. 



Clypeus. In most specimens the suture separating the frons from the 

 clypeus is not clearly marked. The lateral margins of the clypeus are strongly 

 curved outwardly. The clypeus is truncate anteriorly and bears two setae. 



Labrum. The labrum is small, not so strongly chitinized as the frons, 

 and slightly bilobed. 



