Historical illustration, from Greene CT. 1917. A contribution to the biology of the North American Diptera. Proceedings of the Entomological Society of Washington. 19:146–161.
PLATE XVII (BHL link). Illustration is by the author of the paper.
Fig. 1. Mydas clavatus Drury, larva.
Fig. 2. Mydas clavatus Drury, pupa.
Fig. 3. Mydas clavatus Drury, posterior spiracle, enlarged.
Part of narrative on this species, p. 147 (BHL link):
"The larvae of this species were collected at Falls Church, Va. by Mr. T. E. Snyder and the author, in the rotten roots of a dead tulip(*) stump. All the larvae were well below the ground, where the wood was quite moist; they resembled the wood fibres so closely that they might often be overlooked. The larvae are predaceous on Coleopterous larvae and one larva devoured an earth worm placed in the breeding jar. In the same roots were several larvae of the following Coleopterous genera, Alaus, Parandra and Pelagnota (sic = Pelidnota?).
Only one larva pupated, June 1, 1914 and the adult emerged June 27, 1914." (Extensive descriptions of larva and pupa follow.)

(*) By "tulip", the author no doubt meant "tulip tree", Liriodendron tulipifera.