Beedrill is a Pokémon which mostly resembles a bipedal, yellow wasp; however, it only has four legs instead of six and lacks pigment pits. Beedrill's head is round with a slightly pointed mouth, large, red eyes, and black antennae with a sharp bend in the middle. Its forelegs are tipped with long, conical stingers. It stands on its other two legs, which are long, segmented, and insectoid in shape. Beedrill has two pairs of rounded, veined wings, and another stinger on its yellow-and-black striped abdomen.
Beedrill is highly territorial and unlike real bees, Beedrill live in colonies rather than true "hives", and they work together to solve basic problems regarding food, territory and reproduction. As seen in the anime, Beedrill seems to be especially concerned with the welfare of Weedle and Kakuna and it will respond aggressively to those that disturb them. Disturbing one Beedrill will cause the whole colony to attack. It flies at high speed and attacks using the large venomous stingers on its forelegs and abdomen. The two stingers on its forelimbs allow it to use its former signature move, Twineedle. It will take the victims of its attacks back to its nest for food. Beedrill nests in temperate forests and misty wooded areas.
As Mega Beedrill, it gains more defined features. The antennae are shorter and T-shaped. Its eyes become longer and sleeker. It now has three pairs of wings; the uppermost pair is larger with a black trim along the top. Its stingers become longer and larger, resembling lances. Additional conical, black-and-yellow stingers with white tips take the place of its legs. Its abdomen becomes larger, grooved and is attached to its thorax by a black structure. A similar black structure connects its head and thorax. The stinger on its abdomen is now a pale yellow, and it now has black stripes over its entire body. Fast-acting poison is stored in the stingers on its limbs, while the tail stinger produces a slow-acting poison that is used to finish opponents. The instantaneous poisons are instead used to prevent the foe from fleeing.