72 INSECTS AND MAN 



prominent central nipple or tuft (fig. 15, D). This scale is 

 formed by the matting and fusion of the waxy filaments. 

 Twelve days after the larva has emerged the first moult 

 takes place, and, up to this time, the males and females are 

 exactly similar to one another in size, colour, and shape. 

 After the moult an examination of the insects, beneath the 

 scale, shows that both sexes are light lemon yellow and 

 devoid of legs and antennae ; but, whilst the males are 

 elongate and pyriform and possess large purple eyes, the 

 females have lost their eyes and are almost circular, being 

 in fact practically flattened sacs, each with a long sucking 

 bristle springing from the central ventral surface. Eighteen 

 days from birth, the males change to the first pupal stage 

 and assume an elongate oval form, characteristic of the 

 sex. The legs and antennae reappear, together with two 

 wing pads. Two days later, the true pupal stage is 

 reached, and the shed skins are pushed out from beneath 

 the scale. In four to six days more, or from twenty to 

 twenty-six days from birth, the mature males make their 

 exit backwards from the rear end of the scale, beneath 

 which they have rested for a day or two before emerging. 

 To return to the female scale, we find that she moults, for 

 the second time, in about twenty days, and with each moult 

 the cast skin is retained within the scale, the upper half 

 adhering to the scale and the lower half forming a kind 

 of subsidiary scale, next to the bark. Thirty days from 

 birth the females are mature (fig. 16), and if they have 

 then mated, embryonic young may be seen within their 

 bodies, each one enclosed in a membrane. At the thirty- 

 third to the fortieth day the young larvae appear. The 

 whole life-cycle of this insect is passed beneath the scale, 

 with the exception of a few hours' active larval life and 

 an equally brief existence of the fly-like, orange-coloured 

 male. 



Fortunately for fruit-growers, considerable headway 

 against the San Jos6 scale has been made by artificial 



