Solitary bees live by themselves in nests which may be in the ground, or in plant material including woody branches, stems or fruits. The nest chamber is usually packed with pollen and/or nectar and the female will lay a single egg before sealing the opening and constructing another chamber. Usually the chambers are arranged in a linear fashion in a deep tunnel or hole. Each chamber is separated from the next by mud or plant cuttings. The food provided must last the length of the larvae's development which may extend over winter with the young bees emerging in spring.

One type of solitary bee is the leaf cutter bee Megachile rotundata which was introduced to the US around 1930. The mandibles of this bee are modified into cutting implements and are used to carve out disks of leaf which are used to construct the nest chamber. Leaf cutter bees are efficient pollinators for alfalfa crops, because they easily spring the jack-in-the-box action of the alfalfa flower which pops the pollen coated anther out, striking the pollinator on the back. The European honey bee tends to dislike these "hair-triggered" flowers and will chew the base of alfalfa bloom to obtain nectar without pollinating the flower. For this reason, leaf cutter bees are much better pollinators for alfalfa. Since introduction to the east coast, leaf cutter bees have spread and are now found across the country.

The best way to invite leaf cutter bees to your home is to securely bundle a handful of drinking straws together and cut the entire bundle in half length-wise. You now have two "nest sites" that can be hung up under the eaves of a house or garage or fitted neatly under a protected tree branch. Make sure your bundles are secured against wind, and watch for signs of colonization! Here's another page about Leaf Cutting Bees, which talks about using them on an agricultural level for alfalfa crops.

Another well known solitary bee is the Orchard Mason Bee, Osmia lignaria which is native to the United States. This bee is best attracted to your garden by creating wooden nests. Choose a block of wood and use a 5/16th inch bit to drill holes 4 to 6 inches deep and separated from one another by an inch. Place the block of wood under the eaves and watch for bright blue bees to settle in.

Here's an article on Osmia cornifrons another solitary Mason bee introduced from Japan in 1977. This bee performed "...as well as the honey bee..." in pollination studies on Brassica sp.

A Japanese solitary bee, Anthophora pilipes villosula , (the shaggy fuzzyfoot bee) is being studied for pollination of blueberries and fruit trees. You can read more about this "fast flying, long tongued" bee here.