In mid-May, my daughter spotted a wasp nest in our backyard. If you like eating outdoors, wasps can be troublesome, especially later in summer. But because they eat more damaging insects, they tend to be considered beneficial on balance. If, however, the nest is too close for comfort, and it's as big as a basketball, then you might want to get someone else to deal with it. The one we found was only the size of a grapefruit, so I blasted it to smithereens with my garden hose. Thrilling as that was, I later suffered science remorse from not more carefully studying this beautiful thing of nature. Hence this post.
All in Black and White
The bewildered former residents were black and white, probably meaning they were Dolichovespula maculata, commonly known as bald-faced hornets, even though they are not hornets (they're yellow jackets, even though they are not yellow...go figure). They build their nests above ground and live in many parts of North America, but not where it's too dry. Not a problem in Vancouver.
Warm spring temperatures rouse fertilized queens that have spent a secluded winter under a piece of bark or some other protected nook. To begin building a new nest, a queen uses her jaws to scrape bits of fibre from woody sources: plants, logs, cardboard or fences. She breaks down the wood fibres in her mouth with saliva and water to produce a pulp that usually dries as a strong gray paper, though sometimes different colours appear, depending on the source of fibre.
Location, Location, Location
The queen finds a quiet, out of the way place to build a nest. If it's in a tree or shrub, the nest often incorporates plant twigs, which makes the nest stronger and harder to see. It might not be noticed until the leaves disappear in the autumn. In our case, the nest was under a roof ledge.
This New House
The queen builds hexagonal cells, which, as in bee hives, optimizes the use of materials as well as creates a spherical waterproof envelope around them. The hive is vented at the top to help with climate control and open at the bottom. I did notice this wondered why it looked unfinished.
Into each cell, the queen lays a fertilized egg that develops into a dutiful, infertile daughter. The queen raises the first brood herself, collecting prey to feed the young. Once they emerge as winged adults, however, the offspring become general labourers—foraging for food, feeding the young, guarding and enlarging the nest, while the queen focuses on egg-laying.
The workers eventually enclose the basketball-sized nest with an entrance low on one side. The nest can eventually support several hundred denizens with three or four tiers of brood cells. In some areas, squatters like Ichneumon wasps or cockroaches can also hang out in them.
Circle of Life
From July to September, the reigning queen lays fertilized eggs that develop into future queens and unfertilized eggs that become male drones. In the fall, these mature and fly off to mate with royalty from other colonies. The rest of the colony soon dies off, including the original queen. The nest decomposes, over the winter, if birds haven't already torn it apart in search of grubs. In more tropical areas, the nests may get reused.
If you have any wasp encounters to share, add them in the comments.