Monday, August 23, 2010

Wasps Are Eating My Cake

The German Wasp, Vespula germanica
August in Ireland has a lot to recommend it: long, lazy evenings, (relatively) good weather, abundant free fruit in hedgerows. As a month though it does have a major drawback – wasps, sticking their faces into anything remotely sweet. Buzzing around mineral cans and ice lollies up and down the country, they are not only an annoyance, but also pose a risk to ones self as wasp stings are designed primarily to repel vertebrate attacks with little if no effect on other insects (Schmidt, 2009 Encyclopedia of Insects pp. 1049-1052). Easily the most numerous to be seen engaged in this activity are the very similar Common Wasp (Vespula vulgaris) and the German Wasp (V. germanica) (Chinery, 1997 Collins Gem Insects, pp. 234). Social, nest building wasps, these can reach very large numbers in the presence of foods, especially those with a high sugar content.

The animals engaged in this activity are workers, which normally receive sugary trophallactic secretions produced by larvae in response to food provided to them. Around August however, all the larvae have pupated, with the result that the workers must find their sugar rush somewhere else. Thus they descend on our picnics and barbecues to gorge themselves. And as well they might, because come winter they will all die away, the cold weather putting paid to them, along with any males and the previous year's queen. New queen wasps that were hatched between August and September will have mated at this time and hibernate over winter to begin new nests in the spring (Archer, 1985 Journal of Animal Ecology 54 pp. 473-485).

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