Marvels of Insect Life. 



Photos by] [E. Step., F.L.S. 



Beetle and Ant. 



A Uraziliaii beetle is here compared with one of 

 the largest ants from the same region. The 

 limbs, antenna?, and jaws, though agreeing in 

 number and in general structure, yet present 

 considerable modifications of form. The ant is 

 twice the size of life ; the beetle is only 

 half the actual size. 



si.x or eight. All the winged Insects pass through 

 a series of changes, called metamorphoses, after 

 they leave the egg, in the last stage having their 

 wings fully developed. Spiders pass through their 

 developmental stages before they leave the egg, and 

 after hatching merely increase in size without 

 change of form. Insects have only three pairs of 

 true legs ; spiders have four pairs. 



Owing to the fact that the segments of which 

 an Insect's body is composed are strengthened bv 

 the secretion in the outer skin of a substance called 

 ("hitin — which gives it firmness and serves for the 

 attachment of the muscles — expansion of these 

 segments to meet the growth of the internal parts^ 

 is impossible. The difticulty is met b\' the thro\\ing 

 off of the old integument, after a new one has 

 been formed beneath. The new one, before the 

 cliitin has hardened, expands sufficiently to permit 

 of a certain period of new growth, and it may be 

 said that when an Insect has thrown off an old 

 skin the new one is much larger than is necessary 

 to accommodate the internal parts. This case 

 of chitin reaches its highest development in the 

 beetles, where it forms a hard, rigid armour ; but 

 it is also present in the soft, pliable skin of the 

 beetle's grub, and in that of all other grubs and 

 caterpillars. Let it be clearly understood that the 

 chitin itself does not constitute the outer covering. 

 As a matter of fact somewhat less than one-half the 

 weight of the skin consists of chitin. This fact may 

 be ascertained by carefully burning, when the 

 iinimal constituents are destroyed, but the chitin 

 remains and, owing to its uniform distribution, 

 retains its form. The dark colour of chitin is due 

 to the action of light. Beetles, etc., on emergence 

 from the clir\"salis are quite white, and remain so if 

 kept in tlie dark. Those Insects which live in total 

 darkness — as wood-boring grubs, cave Insects, etc. 

 — retain their whiteness. 



We have spoken of Insects and their allies 

 having the bodv built up of segments or rings. 

 It must not be sui)i)osed, however, that these 

 rings are separate and distinct. Taking a long 

 cylindrical body, like that of a cater})illar or a 

 dragon-flv for exam]:)le, and making a longitudinal 



