July

Gasteruption jaculator

To be quite honest with you, I have only chosen this species to write about this month because I think it has one of the best names ever! So, why on earth could a species warrant such a name as this?

Well, Gasteruption jaculator is an insect species belonging to the family Gasteruptiidae – a family of parasitoid wasps. But these guys don’t look anything like your common wasp, as their bodies are black with a broad orange band around towards the back end. The males have long bodies, but the most striking feature of this species is the female’s incredibly long ovipositor - a needle-like tubular organ through which she deposits her eggs. This black ovipositor, with its distinctive white tip, is so long that is seems out of all proportion to the rest of the wasp’s body! The overall appearance is that of a beastie that could potentially inflict a serious sting, which of course is not the case!

As we stop to consider this ovipositor, it starts to become a little clearer why this species should have been given this wonderful name. Gast comes from the Greek “gaster” meaning stomach, and eruption of course means to “issue forth suddenly and violently”. The word Jaculator comes from the Latin meaning a Roman javelin thrower. So there we have it – a javelin-like instrument that can issue forth something from inside the wasp!

This is how it all works. The female finds nests of various solitary bees or wasps, and will then spend some time assessing each hole. She does so, it is thought, by feeling for vibrations from the grubs moving around inside, as the nest hole will have been blocked up to protect the grubs. Having decided on a suitable nest hole, she pushes her long ovipositor through the blocked-up entrance into the nest, depositing her own eggs next to the bee grubs. Very soon the eggs hatch and immediately the young start to feed on the grubs within the nest. They will also consume the food larder of pollen and nectar, left there for the bee grubs to feed on.

The fully grown larvae stay in the bee hole over winter, pupating in the spring and hatching out from May through to September, so they can be seen throughout the summer months, nectaring on a range of plants. This long summer hatching period enables the female to choose a wide range of solitary bee and wasp hosts to target for raising her own offspring, ensuring that her eggs are quite literally not all in the same basket. It also means that they can, to a certain extent, avoid being attacked themselves by other parasites, which might be the case if they all hatched at the same time.

Many people are now buying “bee homes” from garden shops and the like, in order to attract red mason bees, which are excellent for pollinating fruit trees. (Just as easy to chop lengths of bamboo cane up and tie them together – giving the same home at much less expense!) Should you be one of these people putting up solitary bee homes, then you might like to watch carefully to see if you attract a Gasteruption jaculator into the garden.

Quite fun to casually drop into the conversation, as you sit with friends around a table munching on fine BBQ fare, to keep a lookout for the Gasteruption jaculator that lives in the garden and watch their faces!

Peter Thompson
Advisory

Photo credit: Aleksandrs Balodis / CC BY-SA