60 
WHITE FLIES INJURIOUS TO CITRUS IX FLORIDA. 
Fig. 7.— The citrus white 
fly: Second larval instar, 
ventral vie w . Greatly en- 
larged. (Original.) 
Midway between the anterior pairs of legs in the middle of the body is the fleshy 
mouth papilla from which arise the mouth setae, at first when bent backward reaching 
only to slightly beyond the posterior coxae, but later becoming more elongate. Ante- 
rior to the mouth papilla is the semiovate prostomal plate, extending anteriorly as 
far as a line connecting the antennae, and divided longitudinally by two curved 
sutures into one elongate median and two shorter lateral pieces. At the anterior end 
of the prostomal plate is a pair of small papillae, each papilla 
bearing a small forwardly directed spine. 
On the venter beneath and to the side of the vasiform 
orifice is a pair of spines arising from small tubercles, 
normally directed backward and outward, equal in length 
to the distal tibial spine . 
Second instar larva (fig. 7). — Length, 0.37 to 0.43 mm.; 
width, 0.24 to 0.29 mm. Broadly ovate, dorsum densely 
rugose, all marginal tubercles and spines wanting except 2 
cephalic and 4 anal, the three pairs, counting from the 
1 2 3 
cephalic region, giving the relative lengths: — -, — — , -x-p. 
y.o 4.0 iu.o 
Eyes smaller and less regular in outline than in the first 
instar, but distinctly evident. Antennae greatly reduced, 
unsegmented, directed backward and slightly outward, 
tapering, reaching nearly to base of first pair of legs; on 
inside near base with a distinct spinelike projection, and on 
basal portion with numerous roughenings; legs almost rudimentary, reduced to short, 
stout, fleshy processes without distinct segments, composed of a very stout, tapering 
basal portion, and a comparatively small, rounded, thick terminal disc; the second 
and third pairs of legs on the inner side at the base with a minute spine. Mouth 
parts as in previous stage; prostomal plate anteriorly indis- 
tinct and its pair of spines wanting. Spines on either side 
of vasiform orifice, both on dorsum and venter, as in first 
instar. A marginal pore, on either side of body opposite 
base of first pair of legs, and formed by an upward fold of the 
integument, becomes very evident in this instar. 
Third instar larva (fig. 8). — Length, 0.62 to 0.78 mm. ; width, 
0.43 to 0.58 mm. Very similar to second instar but larger; 
the most striking difference presented by the antennae, which 
have migrated backward so as to arise from a tubercle 
slightly anterior to base of first pair of legs. Antennae im- 
movable, directed mesad for about two-thirds of their length, 
and then suddenly doubled backward so that the distal third 
lies in the same plane as the basal portion. Legs smaller in 
proportion than in second instar and prostomal plate less de- 
veloped, but the marginal pores and anal cleft more fully developed. A waxen 
rod is seen often protruding from the marginal pores. Relative lengths of the mar- 
. , • 12 3 
gmalspmes: _, -, -. 
Fig. 8.— The citrus white 
fly: Third larval instar, 
ventral view. Greatly 
enlarged. (Original.) 
The introductory remarks regarding the general appearance of the 
larva apply with equal force to the young pupa (fig. 9, a, b, and c), 
with the exception that the pupa is larger, being nearly one-sixteenth 
of an inch long, is more easily seen, and on either side of the thoracic 
region 3 distinct curved lines representing the outlines of the legs 
