What kind of insect builds a mud nest?
Dissecting the nest
The recent finding of a nest of a type of wasp excavator of the genus Sceliphron (family: Sphecidae) that builds nests of mud even inside the houses, and on which we have already published an entrance before, has awakened our habitual curiosity to know what was happening inside. The breakage of one of the boxes accidentally allowed a larva to come out.
As we published then, it is a predator of spiders that paralyzes with its bite to serve as food to the larva inside the nest. Constructs individual clay nests, for each of their larvae, but united to each other in remote or little accessible places. The opening of one of those cases showed us its interior filled with immobilized spiders.
We have not been able to specify how many spiders this wasp needs per nest because the voracious larva, giving good account of them, grows in the extent to which the number of members of the pantry decreases, but, in any case, are enough that must need.
As the wasp constructs the different nests, hunting spiders and placing an egg in each case, the abundance of these allows us to verify the different stages in which the different larvae are found during their complete metamorphosis or holometábola. Even, as the copy of the following photos, proceeding in full muda larvaria.
Once the larva has devoured all available spiders, it proceeds to transform into a pupa.
As is logical to think, the lower cases must be in a more advanced phase of their metaphorism and as the wasp, to save barrel, takes advantage of the surface on which builds them, two of these cases, intact, with a pupa each , have been preserved by the time the adult emerges for the exact identification of the species, as well as when this occurs (probably Sceliphron destillatorium).
Presumably they winter in this state until the next spring when adults appear to start a new life cycle.
For an expert on spiders, it would be easy to identify the species on which this type of wasp preys, but it is not my case. Of the different species recovered from the interior of the cases, one of the most frequent ones are those of a voluminous abdomen of greenish tonality.
These other, also frequent in the cases, offer no doubt, these are the small zebra spider (Salticus scenicus) in the center of the photo.