The Collaborative International Dictionary of English v.0.48:

Squash \Squash\, n. [Massachusetts Indian asq, pl. asquash, raw,
   green, immature, applied to fruit and vegetables which were
   used when green, or without cooking; askutasquash vine
   apple.] (Bot.)
   A plant and its fruit of the genus Cucurbita, or gourd
   kind.
   [1913 Webster]

   Note: The species are much confused. The long-neck squash is
         called Cucurbita verrucosa, the Barbary or China
         squash, Cucurbita moschata, and the great winter
         squash, Cucurbita maxima, but the distinctions are
         not clear.
         [1913 Webster]

   Squash beetle (Zool.), a small American beetle (Diabrotica
      vittata, syn. Galeruca vittata) which is often abundant
      and very injurious to the leaves of squash, cucumber, etc.
      It is striped with yellow and black. The name is applied
      also to other allied species.

   Squash bug (Zool.), a large black American hemipterous
      insect (Coreus tristis syn. Anasa tristis) injurious
      to squash vines.
      [1913 Webster]

WordNet (r) 3.0 (2006):

Anasa tristis
    n 1: large black American bug that sucks sap of vines of the
         gourd family [syn: squash bug, Anasa tristis]