from the base of New Latin Tenebrionidae, family name, from Tenebrion-, Tenebrio, a genus of the family (going back to Latin tenebriōn-, tenebriō "someone who does things in the dark [by implication in an underhanded way]," from tenebrae "darkness" + -iōn-, -iō, suffix of nouns denoting persons with a prominent feature) + -idae -idae — more at tenebrae
Note: The genus name Tenebrio was introduced by linnaeus (Systema naturae, Stockholm, 1758, tomus I, p. 417); he used the name for the beetle earlier in Fauna suecica (1746).