When can I do spring clean up on my little bluestem that will,avoid disturbance of a bumblebee nest?

Asked March 18, 2017, 11:06 AM EDT

I read that you should wait a bit in the spring to clean out the dead growth from the little bluestem because bumblebees overwinter there, but I cannot find any reference to when it is ok to do it. Last year when I cleaned up I believe I disturbed a bumblebee nest as there was one frantic bumble bee searching everywhere in the area. I assume she must have had a nest there and I accidentally collected it with the dead materials. So do I wait until May? June? Can I clean it out in April? I like to leave the plants over the winter for interest and to provide food and shelter for the birds and insects so I leave my cleanup to spring. I normally clean out starting in April - depending upon the weather.

Ramsey County Minnesota

1 Response

Apparently mated bumblebee queens hibernate 2-3 inches underground over winter. We haven't been able to find reliable information about likely wintering sites in Minnesota.

This document indicates that on average bumblebee queens in Wisconsin emerge about April 20 but might appear as early as the first week in April and as late as the first week in May.
http://images.library.wisc.edu/WI/EFacs/transactions/WT1954/reference/wi.wt1954.refye.pdf

We don't know what, if any, impact removing the dead growth might have on hibernating bumblebee queens but cleaning up before mid-April should minimize disturbance.

It's possible that the hyperactive bumblebee you observed last year was searching for a place to build a nest rather than trying to find an established nest disturbed by your activities.