JUN 3 1921 



May, 1921. 



The Irish Naturalist. 



53 



VARIATIONS IN THE SEGMENTAL SPINES 

 OF THE FOURTH-STAGE LARVA OF 

 ^ HYPODERMA BOVIS. 



BY G. B. PHIBBS. 



Since the discovery of the newly-hatched maggot, four 

 stages are recognised in the larval history of the Warble- 

 fly. These four stages are very distinctly differentiated 

 ■one from another. There is however some difference in 

 appearance between what is known as the young fourth- 

 stage larva and the *' ripe " maggot. A careful comparison 

 -of the spines, which arise on certain areas of the cuticle. 



Fig, I. Fourth stage Larva of Hypoderma hovis. Lateral Vie\v. x 5 

 Areas of Segments indicated : d, dorsal ; Ld,, latero-dorsal ; lateral ; 

 I. v., latero- ventral ; v., ventral. 



was therefore undertaken with a view to ascertaining, if 

 possible, whether there are not more than these generally 

 accepted four larval stages. It was soon seen, however, 

 that considerable variation occurs in the spiny armature 

 of the full-grown warble maggot {Hypoderma bovis). This 

 is noticeable as regards the number, relative distribution 

 size and shape of the spines. 



