THE WOOLLY WHITE-FLY. 67 



Unless molested or crowded eacli female tleposits her eggs in a com- 

 plete circle (PI, IV, fig. 2), she being always on the inside (fig. 19, c). 

 This arrangement she effects by using her mouth parts as a pivot 

 upon which to rotate Jier body. Since often as many as 3 or 

 4 rows of eggs are present in one circle, it is evident that the female 

 describes several circles while ovipositing before seeking a new place. 

 Although as few as 27 eggs have been coiuited in a single circle and 

 as many as 130 in a circle of 4 rows, it is probable that the larger 

 number does not indicate the maxinuim egg-laying capacity, which, 

 in the case of A. citri, has been found to be 222. 



The eggs are whitish when deposited but soon turn to a dark-brown 

 or blackish color and become partially covered by waxen secretions 

 rubbed from the bodies of tlie adults. They are curved, the concave 

 side being upward (fig. 19, a, h), and in hatching the membranes 

 rupture along the median distal half of the upper surface and do not 

 spring back into place after 

 the larva has escaped. 



The larva after hatching 



crawls about before settling. - c\ n n 



. r\ ^ '^ ^' (? 



It is yellowish, elliptical, with ^^ o 



9 pairs of marginal spines and ^ ' 



4 pairs of short, stout, dorsal 



spines. Soon after ceasing 



to crawl, it develops a short, 



iucoiisj)icuous, marginal wax 



fringe simihir to that of the 



,. . f , , .^ „ Fig. 19.— The woolly white-fly {Aleyrodes howardi): a, 



lirst instar or A. nublfera (tig. Egg, showing attachment to leaf; 6, eggshell, viewed 



20). In the second instar from aliove; c, female depositing eggs in a circle, c. Much 



,, • 11 • ,1 1 enlarged; a, 6. highly magnified. (Original.) 



tiie margmal bristles are lost 



except one anterior and two posterior j)airs, and the legs l)ecome 

 unfit for locomotion as is the case with other aleyrodids. During 

 this instar there develop 6 white abdominal cross-bands and a 

 distinct, white, marginal fringe of wax, varying in width \vith age, 

 often becoming 0.3 mm. wide; aside from these secretions, each of 

 the dorsal spines secretes a long, outstanding waxen rod, of varying 

 length, these rods being at all times characteristic of this instar 

 (see fig. 21). After passing into the third instar the larva, except in 

 point of size, assumes the appearniico of the j)upa; the marginal 

 fringe and abdominal secretions found in the precechng instar remain 

 practically the same, but these are largely or wholly concealed by 

 the long, white, curling, and variously matted secretions which arise 

 from along, but not on, tlie margin of the insect, giving to a leaf 

 infested with this species a woolly appearance (PI. IV, fig. 1) which, 

 when infestation is heavy, entirely conceals tlie insect beneath. These 

 tlu'eadlike secretions are often twice as long as the insect itself. At 



