The cotton or melon aphid, Aphis gossypii (Glove), is one of the most important pests worldwide. The species has at least two specialized biotypes, one on cotton (Gossypiumhirsutum), and one on cucurbitaceous plants. In this study, we determined the preference and the finite increase rates of A. gossypii on 10 host plants of Cucurbtaceae with winged adults. A. gossypii adults originally from cotton significantly preferred two cucurbits, hybrid squash (Cucurbita sp.) and zucchini (Cucurbitapepo zucchini), to other host plants; whereas A. gossypii adults originallyfrom melon (Cucumismelo) preferred cucurbit plants, including melon, cantaloupe (Cucumis meloinodorus), pumpkin (Cucurbita moschata), yellow squash (Cucurbitapepo), tornado (Cucumismelo ‘tornado'), and hybrid squash(Cucurbita sp.) to cotton and zucchini. Interestingly, the aphids originally from melon did not prefer zucchini, but they could survive on this host well. Therefore, zucchini could be an intermediate or the mutual host of the two aphid biotypes, and they might be serving as a bridge host of the two biotype aphids.