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Saturday, 2 August 2014

Good news - we've found them!

A few posts ago, I was talking about the fact that few Lestes damselflies have been seen at Rainham Marshes recently.
In fact, the quite rare species, the Scarce Emerald Damselfly (Lestes dryas), which has been seen at Rainham in the past, has not been seen here for 2 years.
I spent several hours yesterday with Rainham's Warden and a couple of fellow volunteers out on Wennington Marsh searching for both the damselflies and any suitable habitat.

I'm pleased to say that we found both, though we only found 6 individuals in just one stretch of a shallow drainage channel. We weren't able to cover the whole Marsh, so we are hopeful that there are more to be found. Amongst the six were 2 mating pairs and another female ovipositing. I grabbed some images to check ID, and to show what we found.

You can see in these images that the drainage channel was full of emergent vegetation. This is how Scarce Emerald Damselflies like it. Large sections of the channel were also dry and, unusually, this is also beneficial to the damselflies. The larvae spend their time hunting in mid-level open water (all dragonflies and damselflies spend most of their lives in larval form in water), so they might be vulnerable to predation by fish. However, because their pond or ditch dries out by the end of summer, there are no fish! The damselflies get through the dry period in the egg, which the female had inserted into the stems of the vegetation (as you see her doing in the image above) and only hatch in Spring once the water level has risen again.

It would be great if we could have them back somewhere around the trail for us all to see, and I know that the Warden plans to manage some suitable areas for the species.