I have bees that fly under rocks in my garden carrying tubes made from leaves with larvae inside. whatarethey?

Question

the tubes have sections inside with brown goo when split open. they are perfectly circular and the larvae are quite large, about an inch in length. the larvae kind of a milky tan colour. the bees come right before winter and dont return until the next year same time before winter. can anyone tell me what these are?

Answer 1

http://www.einsteins-emporium.com/life/a...

http://www.whatsthatbug.com/

http://www.insectimages.org/

Answer 2

Leaf cutter bees! Family Megachilidae, could be one of a couple different genera but I'm guessing most likely Anthidium or Megachile. I can't be much more specific than that if I don't know the leaves they're using or the location. They cut up leaves (or flower petals in some cases) to create nest cells for the larvae. They're very good as pollinators, mostly non-aggressive and the sting is mild.