What is "phobetron pithecium"

Hag \Hag\ (h[a^]g), n. [OE. hagge, hegge, witch, hag, AS. h[ae]gtesse; akin to OHG. hagazussa, G. hexe, D. heks, Dan. hex, Sw. h["a]xa. The first part of the word is prob. the same as E. haw, hedge, and the orig. meaning was perh., wood woman, wild woman. [root]12.]

1. A witch, sorceress, or enchantress; also, a wizard. [Obs.] ``[Silenus] that old hag.''
   --Golding.

2. An ugly old woman.
   --Dryden.

3. A fury; a she-monster.
   --Crashaw.

4. (Zo["o]l.) An eel-like marine marsipobranch ( Myxine glutinosa), allied to the lamprey. It has a suctorial mouth, with labial appendages, and a single pair of gill openings. It is the type of the order Hyperotreta. Called also hagfish, borer, slime eel, sucker, and sleepmarken.

5. (Zo["o]l.) The hagdon or shearwater.

6. An appearance of light and fire on a horse's mane or a man's hair.
   --Blount.

   Hag moth (Zo["o]l.), a moth ( Phobetron pithecium), the larva of which has curious side appendages, and feeds on fruit trees.

   Hag's tooth (Naut.), an ugly irregularity in the pattern of matting or pointing.

Phobetron pithecium, the hag moth, is a moth of the family Limacodidae. Its larva is known as the monkey slug.