Hag Moth Caterpillar?
My name is Lidia, (I don’t speak english so much) I saw your page ‘What’s that bug’ and I like it, I saw an stranger bug in a tree in front of my house two weeks ago (I live in Panamá) and I was surprised and then I started to search in the web and I found your page, and I now I think that this caterpillar is a Hag Moth Caterpillar or Monkey slug. This is true? Sorry for the bad quality of the pictures. Thanks.
While we cannot guarantee that your caterpillar is the same species as the North American Monkey Slug, Phobetron pithecium, the maps on BugGuide as well as our own letters indicate they are common in Texas. If they are in Texas, chances are quite good they are in Mexico. Since plants and animals tend to ignore international borders, chances are also good they may be found in Central America including Panama. If your specimen is not the same species, Phobetron pithecium, it is definitely in the same genus. It is therefore valid to call your caterpillar a Monkey Slug.