PLATE 1 
Rhagoletis pomonella 
A. —Lateral view of mature larva in third instar. X 10. 
B. —Ventral view of larval head, showing mouth, oral hooks, and sense organs. 
C. —Sense organs of snout of larva, greatly enlarged. 
D. —Vertical view of same sense organs as in C. 
E. —Sense organ at angle of mouth with pair of chitinous teeth on adjacent 
-edge of lip. (See B.) 
F. —Part of an intersegmental band of hooklets on cuticle of larva. 
G. —Two hooklets seen in profile. 
H. —Anterior spiracle of second-instar larva, lateral view. 
I. —Diagrammatic dorsal view of anterior spiracle of third-instar larva, show¬ 
ing closed passage from base of stigmatic chamber to cuticle of body wall. 
J. —Lateral view of anterior spiracle of third-instar larva. 
K. —Three stigmatic papillae of anterior spiracle of third-instar larva, showing 
terminal slit in each. 
L. —Oral hook of first-instar larva. 
M. —Oral hook of second-instar larva. 
N. —Oral hook of third-instar larva. 
EXPLANATION OP SYMBOLS 
1 , prothorax. 
2, mesothorax. 
S , metathorax. 
l, first abdominal segment. 
VIII , eighth abdominal segment. 
An, anus. 
ASp, anterior larval spiracle. 
BW, body wall. 
g, anterior sense papilla on snout of head. 
h, posterior sense papilla on snout of head. 
Hk, oral hook. 
i, sense organ at side of mouth. 
j, teeth on edge of lateral hook pocket of mouth. 
k, median ridge on roof of larval mouth. 
Z, median ridge on floor of larval mouth. 
LH, larval head, external remnant of invaginated true head. 
m, outer stigmatic scar, or closed outer end of passage through which tracheal 
cuticle of preceding instar was shed with cast-off spiracle. 
Mth, larval mouth. 
n , inner stigmatic scar, in base of stigmatic chamber. (See m.) 
PSp, posterior larval spiracle. 
. SpC, stigmatic chamber. 
Tra, dorsal longitudinal tracheal trunk. 
v , remains of passage of stigmatic chamber to body wall, through which tracheal 
intima of last larval instar was shed. (See m and n .) 
