8 4 



INSECT TRANSFORMATION 



seven or eight bead-like segments, the sucking conical mouth 

 with the pair of mandibles and the left maxillary blade modified 

 as piercers, both maxillary and labial palps (absent in the 

 Hemiptera) being present. The short feet ending in bladder- 

 like suckers, have no claws, and the wings, usually present, 

 are very narrow, each with only one or two nervures and 

 fringed with exquisitely delicate and slender bristles. The 

 abdomen, spindle-shaped or cylindrical, tapers to the tail-end 

 (Fig. 45), and bears usually, in the female, a cutting ovipositor. 

 Such an insect, often with its hardened cuticle shining black, 

 a small active creature perhaps only a millimetre in length, 

 lays, in incisions cut in leaves, little whitish rounded eggs 



FIG. 45. BEAN THRIPS (Heliothrips fasciatus). 

 X 36. After Russell, Entom. Bull. 118, U.S. Dept. Agric. 



(Fig. 46 a) whence the young thrips are in due time hatched. 

 These attain in their first stage (Fig. 46 b), a length about 

 half that of their parent, which they resemble in general body- 

 form, but their colour is translucent white and there is no trace 

 of wings. After the first moult, the insect becomes almost 

 as large as the parent, yellowish white in colour, possibly with 

 crimson spots and still entirely wingless (Fig. 46 c). The 

 third stage shows the same general shape and colour, but the 

 body is somewhat strongly bristly, and conspicuous wing- 

 rudiments reach backwards as far as the third abdominal 

 segment (Fig. 46 d). After the third moult the creature 

 appears in its last stage but one (Fig. 46 e), bristly, with narrow, 



