The wings of insects are mostly covered with hairs or scales, several examples of which are given in Plate VIII. Fig. [4] shows one of the scales of the Adippe or fritillary butterfly, exhibiting the double membrane—part of which has been torn away—and the beautiful lines of dots with which it is marked. The structure of the scales is further shown by a torn specimen of tiger moth scale seen on Fig. [16]. On many scales these dots assume a “watered” aspect when the focus or illumination changes, an example of which may be seen in Fig. [15], a scale of the peacock butterfly.
Fig. [11] is one of the ordinary scales of the azure blue butterfly, and Fig. [10] shows one of the curious “battledore” scales of the same insect, with its rows of distinct dottings. Fig. [14] is one of the prettily tufted scales of the orange-tip butterfly, and Fig. [8] is the splendid branched scale of the death’s-head moth. Fig. [19] shows a scale of the sugar-runner (Lepisma saccharína), a little silvery creature with glistening skin, and long bristles at the head and tail, that is found running about cupboards, window-sills, and similar places. It is not easy to catch with the fingers, as it slips through them like oil; but by holding a cover-glass in a pair of forceps, and pressing it upon one of the little creatures, a number of the scales may be caused to adhere to it, and these should be mounted dry for examination. The gnats also possess very pretty scales, with the ribs projecting beyond the membrane.
VII.
| FIG. | |||
| 1. | Tongue, Hive Bee | 18. | Do. Dung fly |
| 2. | Do. Tortoiseshell Butterfly | 19. | Do. Asilus |
| 3. | Do. do. one of the barrel-shaped bodies | 20. | Do. Acarus of Dor-beetle |
| 4. | Head, Violet Ground Beetle (Carabus) | 21. | Claws and Pad, Ophion |
| 5. | Tongue, Cricket | 22. | Wings, Humble Bee |
| 6. | Do. do. | 23. | Do. |
| 7. | Head, Scorpion Fly (Panorpa) | 24. | Wing hooks, hind wing of Aphis |
| 8. | Leg, Ant | 25. | Wing hooks, Humble Bee |
| 9. | Proleg, Caterpillar | 26. | Foot, Flea |
| 10. | Do. do. single hook | 27. | Stomach and gastric teeth, Bee |
| 11. | Proboscis, Fly | 28. | Three teeth of do. |
| 12. | Do. do. “modified trachea” | 29. | Cast skin, Larva of Tortoise Beetle (Cassida) |
| 13. | Part of Foreleg of Water Beetle (Acilius) | 30. | Balancer, Blow fly |
| 14. | Do. large sucker | 31. | Wing, Midge (Psychoda) |
| 15. | Leg, long-legged Spider (Phalangium) | 32. | Do. do. part of a nervure with scales |
| 16. | Do. Harvest-bug (Trombidium) | 33. | Stomach and gastric teeth, Grasshopper |
| 17. | Do. Glow-worm | 34. | Spiracle, Wire-worm |
VII.
Fig. [21] is a scale from the common spring-tail (Podúra plúmbea), a little creature which is found plentifully in cellars and other damp places, skipping about with great activity. Some flour scattered on a piece of paper is a sure trap for these little beings. Fig. [3] is one of the scales taken from the back of the celebrated diamond beetle, showing the cause of the magnificent gem-like aspect of that insect. We have in England many beetles of the same family—the weevils—which, although much smaller, are quite as splendid when exhibited under a microscope by reflected light. The wing-case or “elytron” of a little green weevil, very common in the hedges, may be seen on Plate XII. Fig. [10].
The reader will observe that all these scales are furnished with little root-like appendages, by means of which they are affixed to the insect. Fig. [13] shows a portion of the wing of the azure blue butterfly, from which nearly all the scales have been removed, for the purpose of exhibiting the pits or depressions in which they had formerly been fastened, and one or two of the scales are left still adherent to their places. The scales are arranged in equal rows like the slates of a housetop, as may be seen on Fig. [18], which represents part of the same wing, to show the scales overlapping each other, and the elegant form which they take near the edges of the wing, so as to form a delicate fringe. The long hair-like down which covers the legs and bodies of the moths and butterflies (which are called Lepidóptera, or scale-winged insects, in consequence of this peculiarity), is seen under the microscope to be composed of scales very much elongated, as is shown in Fig. [17], a portion taken from the leg of a tiger moth.