ooO''^^ 



THE WOOLLY WHITE-FLY. 67 



Unless molested or crowded each female deposits her eg^s in a com- 

 plete circle (PI. IV, fio;. 2), she beino^ always on the inside (fi<r. 19, c). 

 This arrangement she effects by using her mouth j)arts as a j)ivot 

 upon which to rotate her bod3\ Since often as many as 3 or 

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

 dc^scribes several circles while ovipositing before seeking a new place. 

 Although as few as 27 eggs have been counted 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 maximum egg-laying capacity, which, 

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



The eggs are whitish when dej)osited but soon turn to a dark-brown 

 or blackish color and become partially covered by waxen secretions 

 rubbed from the bodies of the 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. 

 It is yellowish, elliptical, with <i^ ^ ^c? 



9 pairs of marginal spines and 

 4 pairs of short, stout, dorsal 

 s{)ines. Soon after ceasing 

 to crawl, it develops a short, 

 incons])icuous, marginal wax 

 fringe similar to that of the 



r J. • ,x f A 7, V /fi ^^'^' ^^-"The woolly white-fly {Aleyrodes howardi): a, 



nrst instar or A.. nUOVfera (tig. Egg, showing attachment to leaf; b, eggshell, viewed 



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



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



the margmal bristles are lost 



except one anterior and two posterior pairs, and the legs become 

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

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

 <listinct, white, marginal fringe of wax, varying in width with 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 appearance of the pupa; the marginal 

 fringe and abdominal secretions found in the precethng instar remain 

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

 tlie long, white, curhng, and variously matted secretions which arise 

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

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

 when infestation is heav}-, entirely conceals the insect beneath. These 

 threadlike secretions are often twice as long as the insect itself. At 



