2 
Journal of Agricultural Research va. xxviii, no. i 
There has been much useless discussion in print on the subject of the number 
of segments in the maggot, by writers unfamiliar with the fundamental facts of 
its structure, though the correct morphology of the muscoid larva has been 
known for nearly 60 years, ever since Weismann (53 ) 2 published the results of 
his studies on the blow-fly. That the segment carrying the anterior spiracles 
(PL 1, A, ASp) is the true first body segment is proved by the fact that the stalks 
Fig. 1.—The apple maggot (Rhagoletis pomonella ): A, adult female (X 7); B, female fly puncturing the 
skin of an apple preparatory to depositing an egg; C, section of an apple showing an egg inserted at a> 
and a young maggot tunnelling into the pulp at 6; D, an egg (greatly enlarged) 
of the prothoracic leg buds are attached to its ventral surface (PI. 3, F, L J 
and evaginate froupL it. Likewise the attachment of the other leg buds (PL 
3, F, L 2 , L 3 ) and the buds of the wings and halteres to the next two segments 
proves that these (2 and 3) are the mesothorax and the metathorax. The 
following eight segments (I-VIII) belong to the abdomen, but the last one is 
evidently a combination of the primitive eighth, ninth, and tenth segments. 
The larval head in some species of 
maggots is divided into several parts by 
transverse constrictions, one of which 
has been called Newport’s “segment,”’ 
but such rings are not true segments. 
Moreover, a study of the maggot’s de¬ 
velopment shows that its apparent head 
is, at most, but a small part of the true 
head, and that the mouth hooks are not 
“mandibles” as some writers assume 
them to be. 
The larval head (Pl. 1, A, LH) of the 
apple maggot is a simple cone, sometimes 
suggesting a double structure by a trans¬ 
verse fold which appears when the head 
is partially retracted. The anterior end 
is blunt and snoutlike (Pl. 1, B) and 
bears two papillae (g, h ) on each of its 
anterior angles. These papillae support 
peglike sensory end-organs, shown more enlarged in Plate 1, C and D. On the 
middle of the lower surface of the head is the larval mouth (Pl. 1, B, Mth) from 
which project the two large oral hooks ( Hk ). These hooks lie in lateral pouches 
of the oral cavity formed by median dorsal and ventral tonguelike ridges (k 
Fig. 2.—An infested apple cut open showing the 
tunnels of the apple maggot through the flesh 
* Reference is made by number (italic) to “ Literature cited," p. 33-36. 
