Chalcolestes 2 species

Two very closely related species, which are both restricted to the Western Palarctic (shown in green on the maps). The western species is C. viridis. It has only recently been found regularly in UK but is now turning up in many places in south east England. It breeds in a wide range of still and slow flowing waters. The adults emerge in Spring and early summer. the adults then leave the water and diapause returning sexually mature in the early autumn.

The adults usually oviposit in tandem (see above)  in branches of shrubs and trees that overhang water hence the vernacular name the Willow Emerald. My experience is that the plant is not important, indeed I have found hawthorn (Crataegus spp.) to be the species of choice.

One extremely useful feature is that the females, in cutting into bark, create a visible slot which persists (see above) and can be very useful when searching out new colonies.

There is no blue pruinescence and there is a prominent spur marking on the side of the thorax.
The second species, C. parvidens , is restricted to eastern Europe including Italy. Because of the problems of separation the exact range of this species is not fully known