Transactions of The Royal Society of Canada 



SECTION IV 

 Series III MARCH 1915 Vol. VIII 



On the Nervous System of the Larva of Sphida Obliqua Walker. 

 By E. Melville DuPorte. 



Entomological Laboratories Macdonald College, Que. 



Presented by F. C. Harrison, F.R.S.C. 



Read May 27th, 1914. 



INTRODUCTION. 



In this paper it is proposed to describe the entire nervous system 

 of the full-grown larva of Sphida obliqua Wlk., tracing the distribution 

 of the various ganglia, nerves, and their branches as far as they have 

 been followed. 



This caterpillar is well adapted for dissection because of its 

 comparatively large size, the paucity of hairs on the body, and the 

 relative ease of obtaining a sufficiently large number of specimens for 

 dissection. It is found in the stem of the common broad-leaved cat- 

 tail reed (Typha latifolia L.) which grows abundantly in the swamps 

 in the neighbourhood of Ste. Anne de Bellevue and on He Perrot. The 

 larva pupates at the end of April and imagination takes place a few 

 days past the middle of May. The eggs are laid at this time and soon 

 hatch, the larvae feeding inside the stem of the plant near its roots. 

 Full grown caterpillars may be collected late in the fall, just before 

 hibernation. 



At this time the insect is about 50 mm. long. The head is com- 

 paratively small, flat and strongly chitinized, these qualities rendering 

 it rather difficult to dissect. There are six ocelli on each side of the 

 head. The body is nearly cylindrical and of a neutral shade. There 

 are eight distinct abdominal segments, and of these the third, fourth, 

 fifth, sixth and eighth bear prolegs. Spiracles are borne on the pro- 

 thoracic and on each of the eight abdominal segments. 



The nervous system of the larva is rather generalized ; there is a 

 ganglion for each of the first nine body segments. In the tenth 

 segment, however, there is a fusion of at least two ganglia. The 



Sec. IV, 1914—2*1 



