Illacme socal is a species of millipede in the family Siphonorhinidae.

[1] Known as the Los Angeles thread millipede, it is thin and elongate.

Like all members of the genus Illacme, I. socal is eyeless, lacks pigmentation, has well-developed sensory structures, and displays other troglomorphic features.

[2] The habitat of I. socal is the chaparral shrubland in California and live oak woodlands.

They have been found beneath the humus layer and within the soil matrix.