Are Wasps more Numerous on Terraces at the End of Summer?

By Catherine Crépeau – The Rumor Detector

Agence Science-Presse (www.sciencepresse.qc.ca)

Between July and September, wasps hanging around plates and glasses can make for some pretty disagreeable outdoor meals. Are they always that aggressive? The Rumor Detector finds out. Read on…

More Numerous

Most of the hundred wasp species present in Québec live in solitude and don’t appreciate our food at all. Those that bother us mainly come from three species: the wasp in our photo, the German wasp (Vespula germanica), the common wasp (Vespula vulgaris), and the eastern yellowjacket (Vespula maculifrons). These species live in colonies, where swarms of sterile worker wasps take care of the young larvae and the queen.

Contrary to their distant cousin the honeybee, wasps have to rebuild their colony each year. In the spring the young queen, who has hibernated underground or underneath the bark of a tree, constructs a nest in which it lays its eggs. At the end of the summer the community is composed of several thousand individuals – up to 10,000. So wasps are most numerous at this time of year. This population spike increases the competition to find food, which can give humans the impression that they are more aggressive.

More Available

A second factor comes into play: wasps have more time on their hands from July to September. During the summer, worker wasps have to take care of their larvae. To feed them they need to obtain protein, which they do by hunting for caterpillars, flies, crickets and other pest insects. Wasps also feed on sugary substances. The workers feed off of the larvae themselves, which secrete a substance rich in sugars. This is the main mode of nutrition for adult workers, according to a British group devoted to studying wasps.  

But as summer goes on and the wasp larvae transform into insects, workers find themselves unemployed. And they don’t get their regular dose of sugar anymore. They spend less time around the colony. So they take the opportunity to hang around outdoor patios. They can also be found around flowers: wasps can be as efficient at pollination as some bee species.  

The result is that during summer, worker wasps are so busy they don’t have time to dive into your aperitif or attack your bowl of fruit.

More Aggressive?

Since they only have themselves to defend and are even hungrier for sugar than earlier in the summer, wasps head out to look for sugary foods and fruit trees. But nothing proves that they are more aggressive at the end of summer.

Unless they feel threatened. A wasp that thinks it is being attacked will secrete a substance to beckon its fellow wasps to come and help. And when a wasp is killed, it emits a pheromone that attracts its peers and makes them more aggressive. Since wasps can sting more than once, unlike bees, it’s best to avoid getting them mad.

Normally, the real run-ins with wasps happen when we stumble onto a nest that may be constructed in a tree, the walls of a house or a hole in the garden.

Verdict

Wasps are more prevalent at the end of summer, between July and September, and are more attracted to sugar. But nothing proves that they are more aggressive towards us than normal and are more likely to sting us, unless they feel threatened.

Link to the Original Article

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This article is part of the Détecteur de rumeurs series; click here for other articles in the series.