Structures of Silk Spun by Caterpillars 330 Silkworm 336 Emperor-Moth 342 Spinning Caterpillars 344 CHAPTER XVIII. Structures of Spiders 366 Nest, Webs, and Nets of Spiders 383 Diving Water-Spider 393 CHAPTER XIX. Structures of Gall-Flies and Aphides 398 Hawthorn Weevil 413 Gall-Beetles 415 Leaf-Rolling Aphides 418 Pseudo-Galls 421 CHAPTER XX. Animal Galls, Produced by Breeze-Flies and Snail-Beetles 424 Grub Parasite in the Snail 436 ILLUSTRATIONS. PAGE 1. Eggs of Insects, magnified 16 2. Larvæ 17 3. Pupæ 18 4. Insects in the Imago or perfect state 19 5. Mason-Wasp 23 6. Jaws of Mason-Wasp 24 7. Cuckoo-Fly 25 8. Mason-Wasp's Nest and Cocoons 25 9. Mason-Wasp 25 10. Nests, &c., of Mason-Wasps 26 11. Towers built by Mason-Wasp 29 12. Nests of _Pompilus punctum_ 29 13. _Scolia Xantiana_, and section of its burrow 35 14. Mason-Bee 38 15. Exterior wall of Mason-Bee's Nest 39 16. Cells of a Mason-Bee 39 17. Cells of Mason-Bees 46 18. Cells of _Chalicodoma_ 49 19. Nest of _Synagris calida_ 50 20. Cell of Mining-Bee 51 21. Cells of Carpenter-Bees, in an old post 57 22. Carpenter-Bee and Cells 58 23. Carpenter-Wasp and Cells 62 24. Rose-leaf-cutter-Bee and Nest 71 25.