86 



INSECT TRANSFORMATION 



For further and more specialized examples of this type of 

 life-history we may return to the order (Hemiptera) of the 

 bugs and greenfly, and take one or two families of the same 

 group as the latter. The Snowy-flies (Aleyrodidae) 1 are a 



FIG. 47. SNOWY-FLY (Aleyrodes citri.) 



a, male (side view) ; 6, female (dorsal view) ; c, eggs (one with larva hatching) ; 



d, first-stage larva (ventral view) ; e, cuticle of second instar ; /, " pupa " (rests 

 within cuticle of third instar) ; g, adult (with crumpled wings) emerging, x (a, b, 



e, j, g) 16 ; (c, d) 60. After Riley and Howard, " Insect Life ", V. 



family of little insects with white wings, sometimes present 

 in large numbers on plants whose sap they suck. In these 

 countries only a few species occur commonly out of doors, but 

 they often appear as pests in greenhouses. The head, with 



1 A. L. Quaintance and A. C. Baker : " Classification of the Aleyrodidae ". 

 U.S. Dept. Agri. Entom. Tech. Series No. XXVII. 1913-14. " Contribution 

 to our Knowledge of the White Flies ". Proc. U.S. Nat. Mus. Vol. LI. 1917. 



