A recent newcomer to this area is gradually making its presence felt – a highly industrious wasp, the Black-and-yellow Mud Dauber or Sceliphron caementarium to give it its Latin name, the ‘mason, builder of walls’
Originally from the Nearctic ecozone which covers most of North America, including Greenland, Central Florida, and the highlands of Mexico, the wasp was unknown in Italy until 1990 when due to an accidental introduction it was was first spotted in Pisa and documented by the Dipartimento di Fisica – Universita di Pisa. It has now spread out over the Pisa plain and for some years has been breeding quite successfully here in Barga.
These industrious wasps collect mud to build their nests, typically securing them on hard, sheltered surfaces. While rocky outcrops suit this need in the wild, buildings can be even more attractive and for some reason, marble statues which provide the substrate and protection they require are the prefered site here in the city.
As a female builds her multi-chambered nest she paralyses and transports spider prey to each cell. After laying an egg in a provisioned cell she seals it off with a mud plug. She may then add more mud to cover the entire cluster of cells.
When the egg hatches the larva has a stockpile of spiders to eat. After pupating and overwintering in the nest, the new adult eventually emerges the following spring. While the larvae eat spiders that are provided by their mothers, the adults visit flowers for food.
Accidental introduction of the nearctic Sceliphron Caementarium (Drury) in Pisa province, Italy (Hymenoptera: Sphecidae) – F Strum – Dipartimento di Fisica – Universita di Pisa, via P. Torricelli 2, 56126 Pisa – Frustula Entomologica , vol. 19, no. 32, pp. 176-179, 1996
The nearctic sphecid wasp Sceliphron caementarium (DRURY, 1773) was found for the first time in the plain of Pisa in 1990. The introduction appears to be successful and the species can now be found over an area of about 900 square km around the presumed introduction site.
Filippo Ceccolini & Emanuele Paggetti – Note sulla distribuzione degli Sceliphron italiani con nuovi dati corologici per le specie alloctone – pdf file here