The mud tubes of the Organ-pipe Mud-dauber Wasp (Trypoxylon politum) are a familiar sight amidst the nooks and crannies of Green-Wood’s mausoleums. But, you know, I’ve never seen one of the wasps here! So I’ve been checking this particularly rich assemblage to see if this space might be used again. So I was surprised to come across this Hidalgo Mason Wasp (Euodynerus hidalgo) on August 2nd, stuffing a paralyzed caterpillar into the one of the tubes. Reuse! Interestingly, this species, in the potter and mason wasp subfamily, usually nests in wood. I found a reference to western examples of the species that have been known to re-use such mud tubes made by other species, and one of the authors of that reference noted on my iNaturalist observation that “some species are highly opportunistic in their choice of nest sites.”As the Hidalgo wasp was stuffing prey, this Metallic Bluish-green Cuckoo Wasp (Chrysis angolensis) was hanging around. As the binomial suggests, this is an introduced species. They are cleptoparasitic, laying their eggs in the nests of other wasps. I found one listing of their known targets, which didn’t include the Hidalgo, but perhaps that lists needs to be updated?I’ve been regularly checking this mausoleum when I’m in Green-Wood. On August 10th, noting that the hole the Hidalgo was using was still open, I spotted this new mud conglomeration in another corner. The darker mud means this was just closed off.This Yellow-legged Mud-dauber (Sceliphron caementarium) was too fast for me, but you can see that she has a roundish mud ball that she’s transported from a nearby source of mud. I waited to see if she might return for a better photo.Well, no, but this Common Blue Mud-dauber (Chalybion californicum) appeared and promptly got stuck in not one but two cobwebs strewn about the columns. This species is known to reuse Organ-pipe Mud-dauber tubes. (The original makers don’t seem to, making fresh ones each year.)The wasp pulled herself out of both sticky situations, but look at this small spider ready to eat for a week!This blue wasp’s binomial suggests they hail from California, but they’re widespread across North America. I assume that Henri Louis Frédéric de Saussure, who named the species in 1867, did so after a specimen found in California. The species first seems to have been named in 1763, when it was considered to be in the Sphex genus. One last update: the day after I saw the capped off Yellow-legged, it looks like this, with more mud balls added to the pile.
This blog, as you may know, costs a few hundred dollars a year to host and maintain. I don’t use ads to mar your experience here, but I do take donations.
I understand the construction of the mud tubes if they are horizontal and both sealed, reinforced and possibly disguised when complete. What I don’t comprehend is an acess hole on what looks to be open bottomed and vertically oriented tubes. Are there separate walls sealing separate compartments inside? What keeps the parasitized larvae from falling out the bottom? Are both th bottom and the acdess hole sealed after a larva with egg is put inside? Which first?
Backyard and Beyond 
I understand the construction of the mud tubes if they are horizontal and both sealed, reinforced and possibly disguised when complete. What I don’t comprehend is an acess hole on what looks to be open bottomed and vertically oriented tubes. Are there separate walls sealing separate compartments inside? What keeps the parasitized larvae from falling out the bottom? Are both th bottom and the acdess hole sealed after a larva with egg is put inside? Which first?
Yes, separate chambers inside.