Sphex lucae is a species of thread-waisted wasp in the family Sphecidae.

[1][2][3][4] Sphex lucae is predominantly found in western North America,[5] but specimens have also been collected in Georgia and Florida.

[6]: 34 Entomologist Henry T. Fernald described this wasp as: "Body rather slender; the head and thorax black; the abdomen black to red, the two colors variously mingled in different examples, the males being generally much darker than the females; wings varying from yellowish hyaline with a fuliginous tinge to deep fuliginous with a violet reflection; legs dark ferruginous to black.

"[7] Richard M. Bohart and Arnold S. Menke proposed moving this wasp to the monotypic genus Fernaldina.

[6] The main body of research on this wasp prior to 1965 regarded its propensity for communal roosting on plants.