Biodiversity Report 2017

Every year our resident expert on biodiversity, Dr Martin Angel, provides a report of his observations of wildlife in the area which enable us to track trends in biodiversity over time. They provide an indicator of the health of the local environment and are made available to the Surrey Wildlife Trust and other interested organisations. He has now submitted his report for 2017, which concentrates on moths. 

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The year started well with a mottled umber appearing in our spare bathroom, and a few days later a small tortoiseshell butterfly was flitting round the upstairs windows. This report focusses primarily on moths. After the initial excitement the year got off to a slow start with cold nights persisting well into April. As a result, it was not until mid-May that I caught a running total of 1000 moths and 100 species. The results for this year are skewed, because we moved to a new house in September. This curtailed my activity around the time of the move and also means that my ‘Home’ patch has shifted. The following table summarizes the results of my trapping activities.

Location Trapping sessions Total number of moths Total number of species
Vicarage Hill 48 3763 338
Farnham Heath 7* 820 188
Sable Wood 7* 848 173
Compton Field 9* 1154 243
Middle Bourne Lane 2 494 103
Boundstone Road 22 439 63
Ten Acre Wood 6* 163 37
Ivy at Ten Acre Wood 11 256 22

 *indicate sessions when BCG generator used

The numbers of moths caught at Vicarage Hill up until the beginning of September was similar to previous years. The commonest moths were common quaker (338), brimstone moth (332) lesser broad bordered yellow underwing (220) and brindle pug (96).

(L-R) privet hawkmoth, tree-lichen beauty, antler moth, European corn borer.

Only single specimens of 104 species were caught, some of these had not been caught before in the garden, for example a privet hawk moth (once an abundant moth now in decline), a tree-lichen beauty (an immigrant species that may be becoming established), an antler moth (a heathland rather than woodland moth) and a european corn borer (am immigrant species from Europe). Other interesting records included a red-necked footman, several boxworm moths, a lilac beauty and a beautiful yellow underwing.  Gardeners will be alarmed by the arrival in Farnham of the boxwood moth (Cydalima perspectalis). It has almost certainly been introduced on imported plants. First reported in Kent on 2007; I first caught it in Farnham in 2016, and then in three places in 2017. Its caterpillars completely defoliate box hedges and topiary.

(L-R) red-necked footman, boxworm moth, lilac beauty, beautiful yellow underwing.

The trapping in the Middle Bourne Lane Garden was to demonstrate to the Farnham-in-Bloom judges the rich biodiversity of the garden. The trapping in Farnham Heath was to provide data to the RSPB; in Sable Wood was on behalf of Bruce Callender, and along footpath 73 in Compton Field was to improve our knowledge of its biodiversity so we can monitor the impact of the housing development should it go ahead. Interesting moths caught at these sites included a red sword grass (an immigrant species from Europe) narrow-winged pugs (the dominant species on Farnham Heath early in the year), a gold swift (whose caterpillars feeds on grass roots but the adults do not feed), and a clifden nonpareil that turned up both in our new garden and in Compton Field.

(L-R) Dark sword grass, narrow-winged pug, gold swift, clifden nonpareil.

Catches in our new garden in Boundstone Road have not been great – the light trap has to compete with a nearby street light. But monitoring the ivy flowers at the entrance to Ten Acre Wood for moths has been richly rewarding. However, the large number of queen hornets on the ivy flowers during the day (up to 6 at any one time!) suggests that they will be pose problems when trapping in the wood in the coming summer.

(L-R) green brindled crescent, angle shades, dark sword grass, queen hornet.