Most people have seen mud nests of the Pipe Organ Wasp, AKA
Mud Dauber. Around the home, the nests
are most commonly constructed on a vertical wall or beam. A location favored by female wasps at my
house is on the front porch. The porch
provides plenty of wall surface for nest construction and a roof to keep the
nests dry.
Nests are constructed by the female wasp, a shiny steel-blue
creature with a long thin waist. She
makes hundreds of trips to haul in balls of mud to form into the tube shaped
nests. Once a tube is completed, the
female carries in paralyzed spiders and stuffs them into the tube. Periodically she’ll lay one egg among the
spiders and seal that section of the tube shut with additional mud. Inside each of these sealed chambers, a
single wasp larva will feed on spiders until it is time to pupate. They will overwinter in this fashion and
emerge as adults next spring.
The tube is constructed as a long arched structure, similar
to the design of a Quonset hut. The house
forms the flat floor and the nest walls are built by adding mud fingers running
from the central line of the tube to the house.
Placement of the fingers progresses in an alternating fashion from side
to side. Color differences in the fingers
show that the wasp may visit several different mud sources during the period of
nest construction.
While doing some work to the barn roof, I dislodged several
mud nests from the barn rafters. I
checked out the debris later to see if anything of interest could be found in
the debris. Most of the fallen nests
were old. The few fresh nests all
contained the lozenge shaped cocoons in which the larvae will eventually
pupate. I set undamaged cocoons in a
safe place where they have a chance of surviving the winter and hatching new
wasps next spring.
This cocoon was damaged in the fall. Inside was a wasp larva. The larvae eat just about every bit of the
spiders in their cells. Debris left in
the cell is just a bit of dust.
Some cocoons were very light weight, so I cracked them
open to see what was inside. Most were
filled with debris with no signs of the larva.
Several were full of the shed skins of Carpet
Beetle larvae. Judging by the number of
skins in each cocoon, the beetles must have flourished here.
There are always a few old mud nests on the porch, usually
in the corners. I’ll remove them when
they reach the stage where they begin to crumble on their own, but it usually
takes them a couple of years to reach that stage. I think they’re kind of neat to look at. They remind me of the Mesa Verde Cliff
Dwellings. They’re just smaller and
easier to access.
