The Collaborative International Dictionary of English v.0.48:

Bee \Bee\ (b[=e]), n. [AS. be['o]; akin to D. bij and bije,
   Icel. b[=y], Sw. & Dan. bi, OHG. pini, G. biene, and perh.
   Ir. beach, Lith. bitis, Skr. bha. [root]97.]
   1. (Zool.) An insect of the order Hymenoptera, and family
      Apid[ae] (the honeybees), or family Andrenid[ae] (the
      solitary bees.) See Honeybee.
      [1913 Webster]

   Note: There are many genera and species. The common honeybee
         (Apis mellifica) lives in swarms, each of which has
         its own queen, its males or drones, and its very
         numerous workers, which are barren females. Besides the
         Apis mellifica there are other species and varieties
         of honeybees, as the Apis ligustica of Spain and
         Italy; the Apis Indica of India; the Apis fasciata
         of Egypt. The bumblebee is a species of Bombus. The
         tropical honeybees belong mostly to Melipoma and
         Trigona.
         [1913 Webster]

   2. A neighborly gathering of people who engage in united
      labor for the benefit of an individual or family; as, a
      quilting bee; a husking bee; a raising bee. [U. S.]
      [1913 Webster]

            The cellar . . . was dug by a bee in a single day.
                                                  --S. G.
                                                  Goodrich.
      [1913 Webster]

   3. pl. [Prob. fr. AS. be['a]h ring, fr. b?gan to bend. See
      1st Bow.] (Naut.) Pieces of hard wood bolted to the
      sides of the bowsprit, to reeve the fore-topmast stays
      through; -- called also bee blocks.
      [1913 Webster]

   Bee beetle (Zool.), a beetle (Trichodes apiarius)
      parasitic in beehives.

   Bee bird (Zool.), a bird that eats the honeybee, as the
      European flycatcher, and the American kingbird.

   Bee flower (Bot.), an orchidaceous plant of the genus
      Ophrys (Ophrys apifera), whose flowers have some
      resemblance to bees, flies, and other insects.

   Bee fly (Zool.), a two winged fly of the family
      Bombyliid[ae]. Some species, in the larval state, are
      parasitic upon bees.

   Bee garden, a garden or inclosure to set beehives in; an
      apiary. --Mortimer.

   Bee glue, a soft, unctuous matter, with which bees cement
      the combs to the hives, and close up the cells; -- called
      also propolis.

   Bee hawk (Zool.), the honey buzzard.

   Bee killer (Zool.), a large two-winged fly of the family
      Asilid[ae] (esp. Trupanea apivora) which feeds upon
      the honeybee. See Robber fly.

   Bee louse (Zool.), a minute, wingless, dipterous insect
      (Braula c[ae]ca) parasitic on hive bees.

   Bee martin (Zool.), the kingbird (Tyrannus Carolinensis)
      which occasionally feeds on bees.

   Bee moth (Zool.), a moth (Galleria cereana) whose
      larv[ae] feed on honeycomb, occasioning great damage in
      beehives.

   Bee wolf (Zool.), the larva of the bee beetle. See Illust.
      of Bee beetle.

   To have a bee in the head or To have a bee in the bonnet.
      (a) To be choleric. [Obs.]
      (b) To be restless or uneasy. --B. Jonson.
      (c) To be full of fancies; to be a little crazy. "She's
          whiles crack-brained, and has a bee in her head."
          --Sir W. Scott.
          [1913 Webster] beebalm

The Collaborative International Dictionary of English v.0.48:

bee fly \bee" fly`\ (b[=e]" fl[imac]`), n.
   any dipterous insect of the family Bombyliidae, which eat
   nectar and in some cases resemble bees. Their larvae are
   parasitic on the larvae of bees and other insects.
   [WordNet 1.5 + PJC]

WordNet (r) 3.0 (2006):

bee fly
    n 1: hairy nectar-eating fly that resembles a bee; larvae are
         parasitic on larvae of bees and related insects