THE CITRUS WHITE FLY: LIFE HISTORY AND HABITS. 59 
No marginal wax fringe appears before or after crawling young settles. Cephalo- 
thoracic and thoracic articulations invisible; 8 or possibly 9 abdominal segments are 
seen with little difficulty. Segments at posterior end of body modified by vasiform 
orifice. Latter nearly semicircular in outline, somewhat 
longer than wide, bordered laterally by chitinous thicken- 
ings which do not meet posteriorly; operculum semicircu- 
lar, nearly equaling in size the vasiform orifice itself, cover- 
ing the ligula and bearing on its median posterior margin 
what appear to be two pairs of small spines, the penulti- 
mate pair of which is about twice as long as the ultimate. 
Ligula darker in color and broadly 
crescentic in shape. On either side 
of, and slightly anterior to, the vasi- (r 
form orifice is a short backwardly 
directed spine arising from a small Sy 
tubercie. The two pairs of rounded, j 
simple, reddish-brown eyes, less Gay 
than 0.01 mm. in diameter and 0.096 
mm. apart—a dorsal pair and a ven- 
tral pair—are situated mesad and 
slightly anterior to the fifth pair of | Fic. 4.—The citrus white fly: 
marginal spines, the dorsal pair be-  C™Wling young; first in- 
j ae ; star, dorsal view. Greatly 
ing nearer the margin and slightly enlarged. (Original.) 
anterior to the ventral pair. 
Antenne, legs, and mouth-parts on the venter. Antenne 
anterior and mesad to the anterior pair of legs, 0.1 mm. long, 
Fig. 5—The ciirus white very slender; apparently 4-seemented, articulations between 
fly: Crawling young; first the segments seen with difficulty and frequently that be- 
instar, ventral view. tween the third and fourth entirely wanting, while in a few 
Greatly enlarged. (Orig- : ; 9 2a : 
inal.) specimens the second segment appears to be divided into 
two parts: Segment | short, stout, fleshy; segment 2 one-half 
as wide and twice as long as segment 1; segment 3 narrower than segment 2 and about 
four times as long; segment 4 very slender, less than one-half as long as segment 3, and 
bearing on its proximal posterior side a minute spine, and distally a long spine. Legs 
short, moderately stout, where ex- 
tended about one-third the width 
of the body; coxee very short and us SC 
stout, the two posterior pairs on 
the posterior inner side with a 
moderately stout spine about 
equal in length to the diameter of 
the coxze and directed backward 
and inward; trochanters distin- 
guished with difficulty, about 
one-third as long as wide and 
collar-shaped; femora more elon- 
gate, slightly tapering distally, 
about four times as long BB BeOS Fia. 6.—The citrus white fly: Antenne and left hind leg 
chanters; tibia much narrower, first instar. Highly magnified. (Original.) 
somewhat longer than the femora, 
with numerous short bristles, two on the outer proximal portion longer and more easily 
seen, on the outer distal portion with a long bristle forwardly directed and curving 
inward toward the tip of the tarsi; tarsi short, ending distally in an enlarged disk- 
like process. 


