8o INSECT TRANSFORMATION 



rudiments, now quite prominent, reach back to the second 

 segment of the abdomen. The fifth-stage nymph (Fig. 42 /), 

 is half as long again as the third, with the mesothorax largely 

 increased in size, the wing-rudiments, which reach back to the 

 fifth abdominal segment, showing the courses of the air-tubes 

 that prefigure the nervuration of the developed imago. In 

 the nymph stages of the bug, unlike those of the grasshopper 

 or dragon-fly, the wing-rudiments lie almost flat on the back, 

 the front pair mostly concealing the hind pair as they do in 

 the adult. After the fifth moult the insect reaches the adult 

 state (Fig. 42 g), in which its length is from 5 to 6 mm., so 

 that through the stages of its life-history it grows about six- 

 fold in length, and more than two-hundredfold in bulk. The 

 period of growth from the newly-hatched young to the perfect, 

 winged bug may be reckoned as about four weeks under 

 favourable conditions. 



We may now turn to consider some points in the develop- 

 ment of a group of insects the Termites or " White-ants " 

 which are of great interest on account of the varied forms 

 which different members of the same species assume when 

 fully grown and the complex social life of their families or 

 communities which often become excessively populous. 

 Details of the habits of termites do not come within the scope 

 of our present subject ; it is possible to consider only those 

 features of their form and development which illustrate the 

 methods of external wing-growth. 



Termites 1 are insects with biting jaws like those of grass- 

 hoppers or cockroaches, and slender, many-jointed feelers on 

 the head. The wings, when fully developed, are very long in 

 proportion to the size of the insect, those of the two pairs 

 closely alike, with an excessive reduction of the anal area, 

 with the typical series of longitudinal nervures, and with a 

 network of cross nervules. At the tail-end are a pair of short 

 jointed limbs (cerci) and (in males) a pair of ventral stylets, 

 recalling the arrangement in cockroaches, to which the termites 

 are believed by some students to be somewhat closely related, 



1 See B. Grass! and A. Sandias : " Constitution and Development of the 

 Society of Termites ". Quart. Journ. Microsc. Soc., Vols. XXXIX, XL. 

 1897-8. K. Escherich : " Die Termiten oder weissen Ameisen ". Leipzig, 

 1909. A. D. Imms : " Structure and Biology of Archotermopsis ". Phil. 

 Trans. R. Soc. (B), Vol. CCIX. 1919. 



