Mason wasp’s nests abundant
SMALL limp native orb web spiders, all brightly coloured and beautifully patterned in green, red, yellow and mauve like small brooches, fell onto a woman’s carpet, together with fragments of clay. A black wasp that flew around the area was collected, and the lot sent to me for explanation.
The 14mmlong black flying insect was a mason wasp, Pison
spinolae. In summer, it makes grouped cells of moulded mud, which it fills with native orb web spiders. These it stings to paralyse, as prey for its larvae.
Each cell contains 416 spiders, depending on size, with fewer large spiders or more small ones per cell. The wasp lays a single egg in each cell. The grub hatches from the egg, devours the store of spiders in the cell, and then, about two weeks later, spins an oval elongated matt greybrown cocoon.
These nests of moulded mud are often made on buildings, around windows, doors and ledges and in the folds of hanging coats, curtains, and similar places.
The vivid and beautiful colours of the native orb web spiders that are stored within the cells surprise many people. These are mostly native species in the genera Colaranea,
Novaranea and Zealaranea, although other orb web spiders are taken as well. The most commonly used spiders are
Colaranea verutum and C. viriditas, which have abdomens spectacularly patterned in grey, white, red, orange, yellow, cream and green.
The mason wasp is a harmless native insect. It is still sometimes wrongly called the ‘‘mason bee’’, seemingly because G.V. Hudson misidentified it as a bee in his
1892 book An elementary manual of New Zealand Entomology.
Hudson stated ‘‘This is the true native bee of New Zealand’’ and went on to describe how it fills its clay nests with honey and pollen. However, his illustration is clearly of the mason wasp. Others using this book as a guide made the same mistake (e.g. William Benham, in his 1904 guide New
Zealand Zoology). This wasp’s most frequent spider prey in Dunedin, Colaranea verutum, was itself the subject of a misidentification recently in the
What’s With That? column in this
newspaper.