The Life-History of Osmia Lignaria and O. Cordata, with Notes on O. Conjuncta1

Abstract

Both Osmia lignaria Say and Osmia cor data Robertson are present in the St. Louis region in fair abundance. Both species have a short adult life, and both appear early in the spring. They are not, however, contemporaneous, but the cordata follow close upon the heels of lignaria. Both species have the habit of appropriating for their own nesting activities the abandoned burrows of other insects, which they first clean, and later partition into small rooms. There is diversity in the habits of the two species, however, in the kind of materials which they gather for partitions and plugs, for O. lignaria confines her choice to mud while O. cordata uses a leaf-paste.