Flying tonight

4 Nov 2019

Over the summer months, with the help of moth expert Annette Shelford, we’ve been investigating the night-time visitors to roof of the David Attenborough Building. When the building was redesigned to house the Conservation Campus, sustainability and habitat creation were two of the priorities. Two courtyard gardens planted with native species provide ponds, insect hotels and bird nesting sites. We’ve had several pairs of successfully nesting birds there, including blackbirds. We also have swift nesting boxes in the east tower. This year, the birds showed great interest and have been seen perching on the edge of the boxes- we are very hopeful that next year they will nest.

As well as the courtyards, the roof top is planted with native Cambridgeshire grassland species, in an effort to attract insect and bird life. Every two weeks during the summer months, we set up a moth trap on the south side of the roof. The trap consists of a black plastic tub, which we pack with empty egg boxes. A bright mercury vapour bulb on the top attracts the insects, which hide away in the egg boxes. Early the next morning, we unpack all the boxes to see what’s flown in. The moths are quite happy in the egg boxes- some have even laid their own eggs! (see the picture below) Once identified, we put them among the plants in the courtyard garden and they fly away once warmed up. So far, we have recorded 84 species of moth (as well as dozens of mainly unidentified beetles, bugs and flies!). A keen group of staff come along to help count and identify our finds.

Moths are important pollinators so it’s great to see how much diversity there is even on the harsh habitat of a 6th storey, city centre roof top. Some of our most common finds are Yellow Underwings (of all kinds but especially Lesser); Garden Grass Veneers; Heart & Dart and Dark Arches. But we’ve also had rarities and some quite spectacular looking moths. In July a beautiful Privet Hawk moth- the largest UK species- found its way into the trap; and lots of lovely brightly coloured species including Canary Shouldered Thorn and Ruby Tiger have put in an appearance. Moths are often very creatively named; some of our favourites have included Setaceous Hebrew Character, Dingy Shears, Burnished Brass and Flounced Rustic.

Moths can also be pests and we’ve trapped quite a few. Among them are Box Tree Moths - very beautiful but responsible for a lot of damage to many gardens’ box hedging;  Codling Moths, whose caterpillars you might find in your apples, Chestnut Leaf Miners which are responsible for all the prematurely crispy brown leaves on horse chestnut trees and Bird Cherry Ermines, whose handy-work you may have seen on Jesus Green a couple of years ago when they stripped the foliage from a whole avenue of trees.