Birchanger Wood Moth Survey: the Results

Jono Forgham


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Graeme J Smith, Steve Easby and Jono Forgham of Herts Moth Group set up three light traps within the wood around 8.30pm on the Friday night for a public moth night. Local residents were invited via the Birchanger Wood website and Facebook account, posters within the wood and a mention in the local newspaper.

In total, around 20 people turned up, including four children. Jono gave a brief introduction as to how the traps work and a little on the biology of moths, detailing their evolution and that there are two large groups of moths, split into micro moths and macro moths. The temperature was perfect for a late May night and by 9.15pm the group began wandering around the wood. The children were given pots and a net to see if they could catch any early fliers and the first moth to be taken was a Nemapogon cloacella, the Cork moth.

The traps consisted of 2 Robinson type traps with 125W mercury vapour bulb powered by inverter generators and a smaller Heath type trap running off a 12 Volt battery with a 15 watt actinic tube.

Mothing was slow as it appeared to be quite dark, but a look to the sky proved that it was still too light for most moths, especially the macros to be on the wing. This was a shame as it was getting too late for the children who had to leave around 10pm and it was shortly after this that moths became more apparent, roosting on the sheets that had been set adjacent to the traps.

Illustration of a Pipestrelle bat preying on a moth. Picture courtesy: RSPB

By now, bats could be seen flying, especially around the open spaces of the water tower. Jono had brought his bat detector that amplifies the sounds bats make to guide their flight. By setting the device to a specific frequency the bat can be identified to species by the sound and also by the kilohertz range. These bats were within the range 45 – 52KhZ which showed they were Pipestrelle bats. A larger bat was seen flying within the wood but had disappeared before the detector could be set to the correct range.

By now the group settled around one of the larger traps and Graeme and Jono talked folk through the species. At this point the highlight of the night for most of group made an appearance, a large female Poplar hawkmoth. Other good moths seen included a Figure of 80 and a Brindle white spot, the latter being an uncommon moth for East Herts with only a few records for Bishop’s Stortford, being more common within Broxbourne Woods further south. A moth that uses oak, lime and birch as its larval foodplant.

It was then decided that the traps should be checked, so the group gathered around each trap in turn as the moths were checked roosting on the egg boxes placed inside the traps. They were all counted and listed.

In total, a somewhat disappointing 106 moths of just 32 species were recorded. We had anticipated twice as many but packing up by midnight meant we missed a good selection of the late flyers. Another trapping night towards the end of July will offer a much wider selection of high summer species in considerably larger numbers. However, all that attended seemed to have enjoyed the evening, seeing many moth species for the first time.

Our next event is the Bug Hunt on 22nd June, from 11am to 1pm – meet at the compound by the water tower, Heath Row, Bishop’s Stortford.


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Birchanger Wood Moth Survey, 31 May 2019

0125  Emmetia marginea 2
0140  Nematopogon swammerdamella 5
0148  Nemophora degeerella 1
0216  Cork Moth (Nemapogon cloacella) 30
0224  Triaxomera parasitella 1
0343  Phyllonorycter esperella 1
0417  Argyresthia spinosella 1
0648  White-shouldered House Moth (Endrosis sarcitrella) 3
0661  Pseudatemelia flavifrontella 1
0921  Phtheochroa inopiana 1
0986  Syndemis musculana 1
1082  Plum Tortrix (Hedya pruniana) 2
1174  Epiblema cynosbatella 1
1176  Epiblema trimaculana 1
1392  Udea olivalis 1
1428  Bee Moth (Aphomia sociella) 4
Total Micros 56
0017  Common Swift (Hepialus lupulinus) 20
1654  Figure of Eighty (Tethea ocularis) 2
1727  Silver-ground Carpet (Xanthorhoe montanata) 2
1728  Garden Carpet (Xanthorhoe fluctuata) 1
1764  Common Marbled Carpet (Chloroclysta truncata) 3
1776  Green Carpet (Colostygia pectinataria) 1
1819  Mottled Pug (Eupithecia exiguata) 2
1834  Common Pug (Eupithecia vulgata) 1
1875  Small White Wave (Asthena albulata) 2
1904  Scorched Wing (Plagodis dolabraria) 1
1906  Brimstone Moth (Opisthograptis luteolata) 1
1950  Brindled White-spot (Parectropis similaria) 1
1961  Light Emerald (Campaea margaritata) 2
1981  Poplar Hawk-moth (Laothoe populi) 1
2028  Pale Tussock (Calliteara pudibunda) 1
2064  Ruby Tiger (Phragmatobia fuliginosa) 1
2092  Shuttle-shaped Dart (Agrotis puta) 2
2380  Treble Lines (Charanyca trigrammica) 1
2441  Silver Y (Autographa gamma) 1
Total Macros 46