Bug box: Leaf-cutter bees

I spotted this really unusual insect…is it a hoverfly, wasp, bee? Look closely at the belly, it has a pair “leaf” attachments! It can’t work as camouflage since it’s on the belly and not above. Isn’t it really wierd?

Oh thanks for tip! So here’s what it is: a leaf-cutter bee or Megachile humilis, also called leaf-cutting bee, of the order Hymenoptera, particularly in the genus Megachile, that differ from most other bees in that they collect pollen on their abdomens rather than on their hind legs.

What it’s used for: The solitary female, after mating, makes a nest in soil, a hollow plant stalk, or a cavity in wood, lining it with pieces of green leaf to envelop the brood.

Quick Facts…

• Leafcutter bees are native bees, important as pollinators.
• Leafcutter bees are not aggressive and have a mild sting that is used only when they are handled.
• Leafcutter bees cut the leaves of plants. The cut leaf fragments are used to form nest cells.
• Leafcutter bees nest in soft, rotted wood or in the stems of large, pithy plants, such as roses.

Leafcutter bees are solitary bees, meaning that they don’t produce colonies as do social insects (honeybees, yellowjackets, ants, etc.). Instead, individual female leafcutter bees do all the work of rearing. This includes digging out nesting areas, creating nest cells and providing their young with food. Adult females may live up to two months and lay some 35 to 40 eggs during this time.

Leafcutter bees nest in soft, rotted wood; thick-stemmed, pithy plants (e.g., rose); and in similar materials that the bees can easily cut through and excavate. Nest tunnels may extend several inches deep and coarse sawdust may be deposited at the entrance. This sometimes causes confusion with other wood nesting insects such as carpenter ants. However, leafcutter bees restrict their tunneling to soft, rotted wood and do not cause damage to homes or other wooden structures.

There also are concerns about leafcutter bee nesting in rose canes, excavating the pith of pruned canes. Leafcutter bees sometimes nest in the largest diameter rose canes but cause little damage because they restrict tunneling to the pith and rarely girdle cambium. After the nest is made, the bees collect fragments of leaves to construct individual nest cells. The bees cut leaves in a distinctive manner, making a smooth semicircular cut about 3/4 inch in diameter from the edge of leaves. Although they cut many types of leaves, leafcutter bees prefer certain types, notably rose, green ash, lilac and Virginia creeper.

Leafcutter bees do not eat the cut pieces of leaves that they remove. Instead, they carry them back to the nest and use them to make the nest cells within the constructed tunnels. Leaf-cutter bees construct several cells from the leaf pieces they collect. The cells are positioned end to end in a long burrow. Several circular leaf pieces form the bottom, then oblong pieces are placed along the sides to form a “thimble.” This thimble is then provisioned with nectar and pollen, and an egg is laid in it. Then the bee cuts more circular pieces to close the cell. Once the cell is closed, the bee starts another cell above the first, until the whole cavity is filled. Like all solitary bees, the female leaves the nest after it is closed. The grubs fend for themselves on the nectar and pollen. Then they provide each leaf-lined cell with a mixture of nectar and pollen. The female lays an egg and seals the cell, producing a finished nest cell that somewhat resembles a cigar butt. A series of closely packed cells are produced in sequence. A finished nest tunnel may contain a dozen or more cells forming a tube 4 to 8 inches long.

Links to check out: 1, 2 and 3

So in the photo above, I guess the bee must be carrying the leaves it had cut, and might be building its nest in the stem of the lily?