Bookshelf entomology 2

This is little more than a footnote to my January 2016 post about the insect life to be found in bookshelves in the tropics: I noticed a can of insect spray tucked discreetly in the corner of a bookshelf and moved it to reveal …

The nest-builder is one of our common mud-dauber wasps (potter wasps), probably a Sceliphron like this one.

Accidental artistry

black and yellow wasp

I have been photographing insects for several years now and usually know, for better or for worse, how a shot will turn out. I still get surprises, of course, and most of them are deleted very quickly. This one was a surprise – the combination of lighting, lens and camera settings gave me an effect I didn’t expect – but I rather like it.

The subject is a common mud-dauber, Sceliphron laetum.

Recycled housing

When I saw a maroon and yellow wasp working on an incomplete mud nest, my immediate assumption was that she was building it. In the first photo in this series, one cell is about 3/4 complete and there is a dark area at the edge of the opening which is obviously wet mud.

Wasp approaching mud nest
Approaching the incomplete nest

Mud-daubers (Eumeninae, also known as Potter wasps) collect little balls of mud and stick them in place to make nests in which they lay a single egg (here and here are other species doing it). They place provisions, i.e. paralysed spiders or caterpillars, in it and then seal it and move on. Inside, the egg hatches, grows as a grub-like larva and pupates in a cocoon which it makes within the nest. It emerges from the cocoon and the nest as an adult wasp, and the life cycle begins again.

Wasp working at the nest
Working at the nest

Here she is again, working on the same area. No real progress is evident.

Wasp nest partly demolished
The nest mostly demolished

And here is the nest a while later. By this time it was clear to me that she was not building the nest but taking it away. Why? It was some time before I had an answer, once again from the helpful folk on my Flickr groups.

Wasp nest in final state
The final state of the nest

terraincognita96 said, “It is quite common for Eumeninae wasps to demolish vacated mud nests of the previous season. They bring along a mouthful of water, regurgitate it on the old nest, form a mud ball and take it to their actual building site. The barrel shaped object left behind could be a cocoon of a previous inhabitant?”

So it proved when I removed it to photograph it and cut it open:

cocoon? 5644

cocoon? 5648

That looks like an exit hole at the top, and the lower shot shows a thin-walled cell with a little organic debris remaining inside.

In retrospect, the cocoon visible inside the incomplete nest should have been enough to tell me immediately that this wasn’t normal nest-building, but I had never heard of wasps recycling building materials before. There’s (still) always something new to learn!

Wasp in flight

Wasp, Delta arcuata, in flight
Mud-dauber wasp, Delta arcuata , in flight

This post is by way of an apology to Canon, who made my new telephoto lens. I said a week ago that its image stabilisation was useful but I did underestimate its benefit.
This photo was taken at 1/80 sec, f8.0 and a focal length of 260 mm (nearly full zoom).

The wasp? Delta arcuata, one of our common mud-daubers. Adults stock their nests with caterpillars for their larvae but are vegetarian themselves, feeding on nectar. Many people are frightened of them, but unnecessarily: they can sting but are not at all aggressive.

The forgetful wasp

Mud spots and wasp nests on wall
One morning's work

Not the most attractive photo you’ve ever seen? It’s not the most attractive wall, either, even at the best of times, but something happened to it yesterday morning: a mud-dauber wasp flew into the room with a ball of mud, decided this was a good place for a nest, stuck her mud to the wall, flew off for more mud, flew into the room with a ball of mud, decided this was a good place for a nest but forgot she had already started, stuck her mud to the wall, flew off for more mud, flew into the room with a ball of mud, decided this was a good place for a nest but forgot she had already started, stuck her mud to the wall … etc. Eventually she got as far as a one-third finished nest (bottom), a half-finished nest (middle) and what looks like a finished nest (top). Phew.

I haven’t seen this kind of mistake before although we are familiar with wasps’ very rigid behaviour patterns. The wasp (same species, by the way) which built this nest had to enter the house through the bathroom window, fly through the open bathroom door and into the lounge. If one of us happened to be in the bathroom with the door shut, she would hover, quite baffled, until we opened the door for her.

We are (obviously) very tolerant landlords to little tenants but yesterday’s misguided efforts can’t stay there too long … perhaps we will just leave the finished nest. If all goes well, she will fill it with small spiders (like this nest) and lay an egg in it before sealing it and leaving it.

Here’s our builder at work on the lower of the three nests:

Black and yellow wasp at work
Wasp (Sceliphron sp.) at work