I only see these dudes appear once a year in my yard. That time is usually around mid-April. Usually when they do, it's at night and they stay close to our exterior door light. They are often about four inches long, though strangely this year they were about three inches...a bit smaller than usual, but I think that is because this years batch came out of their cocoon early or something. What was cool was there were four of them hanging out by the light...though come morning only one stayed behind. It was even cool enough to let me pick it up and take some pics of it. Once I did, I put it back...but then it flew away.

I vary rarely find these guys in their caterpillar stage, being that they camouflage real well with the plants.

I usually hate moths...but the bigger they are, the less of a pest they tend to be.

MORE INFO HERE:
http://www.birds-n-garden.com/hummi.....ird_moths.html