Abstract: In the raising and propagation of leaf cutter bees, rectangular nesting blocks molded from thermal plastics and having a number of open-ended apertures therethrough, are used. Each leaf cutter bee chooses one of the apertures in which to raise its sole progeny in the form of a larvae. In a typical leaf cutter bee nesting shelter, there may be several thousand apertures which appear to be identical. In order to orient the bee to its own aperture, the present invention uses a plurality of raised projections or portions on the front surface of the blocks to help the bees find their respective nesting apertures.