'Sphex fly' definitions:

Definition of 'Sphex fly'

From: GCIDE

Sphex \Sphex\, n.[NL., fr. Gr. ???, ???, a wasp.] (Zool.) Any one of numerous species of sand wasps of the genus Sphex and allied genera. These wasps have the abdomen attached to the thorax by a slender pedicel. See Illust. of Sand wasp, under Sand. [1913 Webster]
Sphex fly (Zool.), any one of numerous species of small dipterous flies of the genus Conops and allied genera. The form of the body is similar to that of a sphex. [1913 Webster]