Freshwater jellyfish in France.

This summer we experienced a very long period of drought and two scorching heat waves which are probably the reason for an unusual and little known phenomenon to occur in the Vienne departement along with other parts of west and southwest France! These were exactly the right conditions when the water warms sufficiently for the emergence of a tiny freshwater jellyfish, craspedacusta sowerbii.  

They are normally only seen when they take the form of a small bell-shaped jellyfish known as a hydromedusa and float near the surface of the water but this requires a water temperature of at least 25°C and forms only one part of their interesting lifecycle.

As a jellyfish they are 20–25 mm in diameter, somewhat flatter than a hemisphere, and very delicate. They have a whorl of up to 400 tentacles tightly packed around the bell margin. Hanging down from the center of the inside of the bell is a large stomach structure called a manubrium, with a mouth-opening and four frilly lips. Food is taken in and waste  expelled through the mouth opening.

Click photo to enlarge

Craspedacusta sowerbyi more often exist as microscopic podocysts (dormant "resting bodies"), frustules (larvae produced asexually by budding), planulae (larvae produced sexually by the hydromedusae), or as sessile polyps, which attach to stable surfaces and can form colonies consisting of two to four individuals and measuring 5 to 8 mm.

This species, originally from China (Yangtze River Basin), probably originally arrived in Europe with aquatic plants imported for botanical gardens. In the ponds of Kew Gardens, near London, it was discovered in 1880 by the naturalist William Sowerby. Since then, it has conquered every continent thanks to the trade in aquarium plants.

In France they can be found in slow moving rivers, lakes and ponds, maybe even your garden pond if they have been transported there with pond plants or stuck to birds’ feet.  Should you come across them you need not worry, they present no danger to humans or other mammals.

Chris

Man stung 30 times by Asian Hornets in France

It’s not that Asian Hornets venom is anymore toxic than our native hornet and wasps, or even that they are more aggressive away from their nest. It’s more about where Asian Hornets are increasingly choosing to make their nest.

I’ve chosen a few recent cases to illustrate this.

In Montmorillon, Vienne, a 76 year old man was stung more than 30 times by Asian Hornets in his garden when cutting a small hedge outside his house on the 30th of October 2019.

When his wife came to his assistance he was covered in hornets and she was stung 5 times before neighbours arrived with thick clothing and managed with the use of wasp sprays to get him away from them. He was transported to the hospital by the Pompiers to receive treatment.

The couple had never noticed the presence of the hornets in the hedge which is about 50cm high.

Earlier in the year on 1st August, in the Nantes area another man was stung more than 10 times when he disturbed an Asian Hornet nest in the water meter box and fortunately suffered no serious effects, however the day before at Grayan-et-l'Hôpital, Gironde, a woman died following multiple stings when she disturbed an Asian Hornet nest at about 1.5 metres from the ground when going to her post box.

In these and most other cases attacks occur when nests are disturbed, whether that is Wasps, Bees or Hornets. I have myself suffered the consequences of putting a brush cutter into a wasp nest at ground level and know how easy it is to hack away without first looking for any obvious nest activity. 

What’s becoming increasingly clear for anyone that has been following the evolving situation with Asian Hornets year on year is that they are increasingly making their nests close to the ground. This inevitably leads to an increase in attacks. (European Hornet nests are always under cover in buildings or hollow trees making accidental disturbance less likely).

Other than in a handful of cases a year in France very few people actually die from stings.

More about stings LINK HERE

Chris