_Aprophora_, spume-bearer, 82. _Arethusa bulbosa_, orchid, 175. _Argiope_, field spider, 8. Aristolochias, 119. Aristotle, 23. Arum, wild: --Position of the anthers, 141; progressive stages of change, 142. _Asclepias cornuta_, milkweed, 227. _Asilus_, "robber-fly", 8. Axell, a follower of Darwin, 116. Bees: --The drone of, 5; a counterpart of clover; dependence of clover on, 117; manner of approach, 121; black-and-white banded, 126; approach to the blue-flag, 131; experiment with the bumblebee, 209; his escape from the flower, 210; manner of cross-fertilizing, 212; manner of conveying the pollen, 218; his difficulties with the milkweed flower, 233; the cumbersome handicap, 234; destroyed by the milkweed, 235. Beetles (_Cicindela_), tiger, 68. Birds: --Swifts, 5; robin, 5; vireo, 5, 45; indigo, 5; chat, 5, 40; oriole, 5, 32; red-headed chippy; barn-swallow, 6, 28, 39, 40; cuckoo, 23; "kow-bird"; cow black-bird; bunting, 27; song-sparrow, 30, 40; Maryland yellow-throat, 28, 45; Wilson's thrush; chewink, 32; fly-catcher; bluebird; oven-bird; cat-bird; phoebe, 40; bobolink; "reed-bird," 53; humming, 227. Birds' nests: --Flimsy structure of the cuckoo's, 26; song-sparrow's, 30; oriole's swinging hammock; cobweb structure of the vireo's, 32; size of yellow-bird's; summer yellow-bird's beautiful home, 47; a four-story house, a possible fashion in featherdom, 51; pipit's, 35; wood-sparrow's, 37. Bittersweet (_Celastrus scandens_), queer little harlequins on, 9; its scarlet-coated seeds, 88. Blackburn, Mrs., quoted, 35. Blair, Patrick, his claims concerning pollen, 111. Blossom ceremonies, 119. Blue-flag, its hidden anthers reached only by the bumblebee or large fly,129; manner of the bee's approach, 131. Burroughs on wren-building, 17. Butterflies: --Great yellow swallow-tail (_Papilio turnus_); red admiral (_Pyrameis Atlanta_); small yellow (_Philodice_); semicolon (_Grapta interrogationis_); comma (_Vanessa comma_), 153; orange; white (_Aphrodite_), 154; white cabbage (_Pontia oleracea_) 153. _Cactus_, prickly-pear, its golden bower, 118. _Collinsonia_, horse-balm, 136. Caterpillars, 10, 14, 15, 62. _Celastrus scandens_, bittersweet, 88. _Chamaelirium luteum_, devil's-bit, 133. Chipmonk, 6. Cicada, victim of the sand-hornet, 77; manner of depositing its eggs; period of transformation, 97; time of hatching, 100. Cicindela, tiger-beetle, 68. Clover, cause of failure of crop in Australia, 117. Cobwebs: --A dusty prize; a two year's span, 7; a mixed assortment in, 8. Cone-flower (_Rudbeckia hirta_), 138; embryo seeds; arrangement of the anthers, 139.