[Stinging Insects] Fixer Uppers...Bee & Wasp Style

Some of the images that come to mind when we hear the term “fixer upper” applied to a house that is up for sale probably include discolored or peeling paint, warped shingles, cracked stucco, leaky basement walls, dysfunctional plumbing and inadequate electric wiring. But what if we are not talking about a house — at least not a house for people? What if we are talking about a nest or burrow? Let’s sneak a peek at some opportunistic bees and wasps that possess some skills at locating and rehabbing the vacated domiciles of other species.

First listing: “Plenty of room; natural wood walls; all the hard work has been done; remodel to taste.”
On occasion, pest management professionals will encounter giant resin bees (Megachile sculpturalis, Figure 1) entering and exiting the previously treated and abandoned galleries of carpenter bees (Xylocopa species). These large relatives of leafcutting bees (Family Megachilidae) are very similar to the black and yellow eastern carpenter bee, X. virginica. However, the giant resin bee is more slender and the females utilize resin (instead of sawdust-like wood fragments) to form the partitions between the brood cells within the tunnels that had been excavated by the original occupants. Furthermore, neither male nor female giant resin bees hover menacingly near their entry holes as male carpenter bees do. (One theory as to why male carpenter bees do this is to aggressively drive away certain species of bee flies, the larvae of which parasitize the larvae of carpenter bees.)
The large black and ivory mason wasp, (Monobium quadridens, Figure 2) also has a fondness for rehabbing the tunnels of carpenter bees. The female wasps use mud to partition off their brood cells in the shafts and to coat the inner surfaces of the galleries, even to the rims of the entry holes. Mason wasp mamas provision the brood cells with paralyzed caterpillars, ensuring a fresh food supply for the larvae.

Second listing: “Lots of cozy rooms; walls nicely papered or mudded; some patching required.”
As a rule, paper or umbrella wasps (Polistes species) of the northern U.S. do not reuse the paper nests left over from the previous season. This rule has been broken by the now familiar dominulus paper wasp (Figure 3) that was introduced to the East Coast from Europe back in 1981. On occasion, overwintered P. dominulus females have been observed to reclaim last year’s paper nests and build upon them after patching the defects with a little masticated wood pulp. Some species of leafcutting bees (Family Megachilidae) spare themselves the trouble of excavating tunnels in wood, stems or soil by claiming the abandoned nests of Polistes paper wasps and Sceliphron mud daubers. PMPs may encounter second-season paper wasp nests bearing colorful cell caps fashioned from discs excised from leaves and blossom petals (Figure 4). The female bee creates protective coverings for her brood cells by cementing these discs to the outer rim of each paper cell that contains one of her eggs and its provision of nectar-soaked pollen, or “bee bread.” Likewise, leafcutting bees sometimes utilize old nests of the black and yellow mud dauber, Sceliphron caementarium, in which to rear their larvae. In such instances, the rehabbed mud cells are lined and the emergence holes are capped with discs cut from leaves and petals (Figure 5).

THIRD listing: “Comfy living room for social setting; well-insulated.”
From time to time PMPs may be called upon to deal with colonies of bumble bees (Bombus species, Figure 6) or yellowjackets that have moved into previously occupied bird houses which contain twigs, yarn, tissue and other nesting materials. Female bumble bees and yellowjackets find protective cavities filled with insulating material very accommodating during the springtime search for nesting sites. Abandoned rodent burrows that contain nesting materials or provide adequate space for colony growth similarly appeal to bumble bees and yellowjackets as nesting sites.
INTERESTING ENCOUNTERS. Insects are opportunists and bees and wasps are no exception. We PMPs may encounter some interesting situations that involve some species occupying the abandoned nests of other species. In such instances, we can benefit from an understanding of what is going on in nature. Sometimes customers are impressed when they discover that their pest management provider possesses a knowledge of ecology that surpasses what is necessary in order to control pests.

Figures 1-6 courtesy of author Gerry Wegner, technical director for Varment Guard Environmental Services, Columbus, Ohio.