I have a little wooden bee house with tiny holes. It used to hang by the catalpa tree and had some activity, but it fell down and now it’s hanging on the crab apple, which is near various perennials including salvia, hosta, coral bells and coneflowers. I have noticed that every hole is now being used — you see some sort of sticky substance on the hole — but now I’m seeing tiny, short sticks in the holes. So I had to do some research.
First: Solitary bees, unlike hive-inhabiting bumble or honey bees, nest in burrows and tunnels in the ground, in hollow plant stems, or in tree holes, and in bee boxes fashioned to have just the right size of holes to attract these bees.
A female, after mating, places pollen and nectar into the “holes” and then lays a single egg in each “hole.” She then leaves — and the young bees emerge the following spring.
These solitary bees, most of which are native, use various substances from the wild to build their nests — leaf pulp, pollen and other substances. My perfunctory research has not shown anything regarding solitary bees putting tiny bits of sticks into the holes. There are some tiny wasps that use the bee boxes, too.
If you know anything more about solitary bees and bee boxes, I’d love to hear it.