The bees (and other insects) play a lesser role in fertilizing the vine, this is mainly done by self-pollination or self-pollination (see also in detail under flowering). Bees are insignificant pests of the vine. The mouth parts of the bee are lick-sucking. The very small upper jaws chew, the lower jaws and the lip palpies form a suction tube with which nectar can be absorbed from the blossom. Wasps, on the other hand, do not have a trunk for sucking nectar, but biting mouth parts with paired upper jaws (mandibles) and lower jaws. In contrast to wasps, bees cannot bite open the skin of the grapes, but only press it open with their head at fine hairline cracks, where they then suck up the sweet sap that escapes. However, they also participate in the preparatory work of the berries bitten by wasps. See also under beneficial insects and vine enemies.