I have heard those can be pretty bad. I see one every now and again around here in the citrus trees. So I try to scope out anywhere I stick my hands, just in case.
I posted a thread and pics of one a couple of years ago. ->
http://www.faunaclassifieds.com/foru...d.php?t=670800
I don't know what the one above in the pic is, but you can see the swelling of some sort of venom reservoir below each of the needles in the closeup pic. I'm guessing it means business.