Medium:

Nests of the mud dauber wasp.

A mud dauber is a type of wasp that builds these amazing nests out of mud. The female mud dauber will look for a patch of moist soil, and will use her legs and jaws to form a ball of mud. She then carries it back to the area where she has chosen to build her nest & continues to gather balls of mud and pack them together until it has formed a glob of mud big enough for her nest. Now the wasp will drill holes in the mud to create these tube like chambers. At this point she goes in search of spiders to supply her nest. She will find a spider and sting it. The sting paralyzes, but does not kill the spider. The mud dauber then carries the live spider back to her nest and places it in the chamber. The female will do this repeatedly until she has a dozen or so paralyzed spiders packed into a single chamber. At this time, she lays a single egg in each chamber and collects more mud/clay and seals the holes. Eventually the mud dauber egg hatches and the larva, or grub, crawls around until it finds the first spider. It bites the spider (which is still alive) near its waist and begins sucking out the spiders fluids and internal organs - the heart and nervous system are the last organs to be consumed. Then the grub moves to the next spider and continues to feed. By the time the larva has consumed all or most of the spiders, it has molted several times and significantly increased in size. At this point, the larva pupates and develops into an adult mud dauber, chews through the clay sealing the nest chamber and starts the cycle all over again.

The blue mud dauber feeds primarily on the venomous black widow spider, they fill each cell with up to 30 spiders, with about 20 cells per nest that’s about 500 spiders eaten...making it a great natural pest control against a dangerous venomous spider.