Author: More than a Dodo

What’s on the van? – Social wasp

This week’s What’s on the van? comes from James Hogan, of the Museum’s Hope Entomological Collections.

Social wasps are a group of insects belonging to the family Vespidae. In Britain we have 8 species of social wasps (species of Vespula and Dolichovespula) and the hornet (Vespa crabro).

Social wasps are viewed rather negatively by many people, perhaps understandable considering their stings and habit of building nests in houses. Despite this, I would argue that social wasps are much maligned creatures and play very useful roles as pollinators and pest controllers in the garden. During much of the spring and summer, social wasps are working away unseen, consuming large amounts of other insects such as flies, caterpillars and aphids. It is only in late summer when their normal food supplies are running out that they can make unwanted visits to picnics.

In a wider and less human-centred context social wasps are part of the food chain, providing food for other animals such as birds and spiders. One very interesting aspect of the ecology of social wasps is that their nests provide a home for a whole range of insects found nowhere else. Two good examples are some of Britains largest hoverflies (species of Volucella) and the strange ‘paradox beetle’ (Metoecus paradoxus). The paradox beetle (Metoecus paradoxus) is a parasite of social wasps. This particular specimen was collected from a nest in a house in Yeovil.

So spare wasps a thought before reaching for that rolled-up newspaper!

What’s on the van? – What a gem!

This week’s What’s on the van? comes from Monica Price, Assistant Curator of the Museum’s Mineralogical Collections.

What is that fine large blue gemstone on the van? Did you guess it was a sapphire? You were absolutely right; it is after all, the most famous of all blue gemstones. But did you know that sapphire is not always blue? It can be yellow, green, purple, pink, even colourless!

Sapphire is the name given to nearly all the coloured gem varieties of corundum, a mineral composed of aluminium oxide. Corundum is one of the hardest of all minerals and is used in industry as an abrasive. It is found in various aluminium-rich igneous and metamorphic rocks and it is so hard that it resists breakdown when the rocks undergo erosion by rivers and streams. Instead it accumulates in river gravels, which can be mined for gem quality crystals.

Most corundum is rather drab, not very exciting at all. Only the best coloured and least flawed crystals are suitable for cutting as gemstones. The colour in blue sapphire is due to a tiny amount of titanium and iron. When corundum contains a tiny amount of chromium instead, it is a beautiful shade of red, and it has a name of its own – ruby. Ruby and sapphire are simply different coloured varieties of exactly the same mineral!