Moth Surveys

Moth Survey 2017

Moth Survey at Highdown Gardens, Friday 14th July 2017

Survey by: Richard Poxon,
Member of the Society of Amateur Entomologists

This year's survey took place on the evening of Friday 14th July 2017. Further trapping sessions took place both before and after the survey evening to capture and monitor other species as well as migrants that appeared during the summer and autumn period.

Setup for moth survey (340)

A Robinson Pattern Light Trap was used to attract the moths. A petrol generator was used to power the trap. Around ¾ of the captured moths were released back into the same area at sundown on Saturday 15th thus avoiding any predators that might take advantage of the free meal. Remaining new moths were kept in my garage while identification took place over the coming few days before being released back into the gardens. The moths remained within their natural habitat.

Once again this year gave rise to a somewhat varied summer with a prolonged warm spell at the beginning followed by rather inclement weather until the August bank holiday. Friday the 14th July was a pleasant evening with temperatures around 14C and overcast during the early evening with virtually no wind. The cloud had cleared by midnight and the temperature remained steady. This summer moth season at Highdown has proven to be reasonably productive. Most of the species now recorded in the species list made an appearance at some stage during the summer months although as is often the case, not necessarily on the survey night. I am pleased to report a small increase in numbers compared with last year's survey but still not the results recorded during 2013 and 2014. At the time of writing I have only been able to add 1 new species to the list this year.

The data in the 'core' species list (see below) has been colour coded in 'traffic signal' style to indicate 'red' for those species that were absent 'yellow' for those species who's numbers remained the same and 'green' for those showing an increase. Surveys focus on the 'core' list from 2008 but as before I remain on the lookout for any species that don't look familiar in order to add them to the Highdown Species list total which now stands at 190 species to the end of 2017.

PDF FileHighdown Gardens - Moth species list 2008 to 2017 (132KB)

It has been another reasonable year for migrants. Last year's large influx of 'diamond back' was not repeated but I did catch my first 'box tree moth' albeit at home in my garden in Angmering. The Box Tree Moth was first reported in London in 2008 and is a suspected import from the far east. It has since spread to the south coast and areas around London. The moth is a major pest of Buxus topiary trees and if the larvae are found they can completely defoliate the tree. The pupae of this moth can survive temperatures of -30C so are not killed off by our long winter period. It now looks as if they are here to stay and will no doubt become a serious pest to our stately homes and ornamental gardens where Buxus is prevalent. As far as I'm aware Highdown Gardens has no Buxus trees but pheromone traps have proved to be a reasonable preventative measure to tackle this invasive species should the need arise.

Some of the moths identified in 2017 include the Blairs Mocha Moth (left) and the Light Emerald Moth (right):

Blairs Mocha Moth (left) and Light Emerald Moth (right)

and the Scarce Bordered-Straw Moth (left) and the Peach Blossom Moth (right):

Scarce Bordered-Straw Moth (left) and Peach Blossom Moth (right)

Persistent Southerly winds always bring the best migration results and Highdown Gardens is very well placed to monitor movement. Migrant moths crossing the sea will land and rest when they reach land. They may also be attracted by lights from shipping and enjoy the free lift to reach foreign shores although the 80 mile crossing from France is of no challenge to a small moth at 10,000 feet being blown along in a steady 40mph wind. Add to that its 15mph flight speed! It's easy to understand how they are able to travel large distances in a relatively short time. The Convolvulus Hawk is a true master of this and has a normal flight speed of 35 to 40mph! With wind assistance that's 80mph ground speed when at altitude and rather faster than the ferry!

Once again I would like to thank Jo Hooper and Worthing Borough Council for their kind permission to carry out this exercise and I very much look forward to the ongoing survey.

Richard Poxon

See also photos of wildlife at Highdown Gardens

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Moth Survey 2016

Moth Survey at Highdown Gardens, Saturday 16th July 2016

Survey by: Richard Poxon,
Member of the Society of Amateur Entomologists

This year's survey took place on the evening of Saturday 16th July 2016. Further trapping sessions took place both before and after the main survey evening to capture and monitor other species as well as migrant moths that appeared during the summer and autumn period.

Setup for moth survey (340)

A Robinson Pattern Light Trap was used to attract the moths. A petrol generator was used to power the trap. Around ¾ of the captured moths were released back into the same area at sundown on Sunday 17th thus avoiding any predators that might take advantage of the free meal. Remaining new moths were kept in my garage while identification took place over the coming few days before being released back into the Gardens. The moths remained within their natural habitat.

I try to select a night with favourable conditions although sometimes the moths feel differently and although not an ideal evening I have chosen the evening of the 16th July as it produced a fairly large catch compared with the preceding days. The weather was settled with low cloud cover and an evening temperature of around 17°C. The wind was from the south west at 4kts.

From a moth trapping point of view this summer at Highdown has proven to be reasonably productive. Most of the species now recorded in the species list made an appearance at some stage during the summer months although as is often the case, not necessarily on the survey night. I was unable to report similar numbers to those encountered in last year's survey but I have been able to add 8 new species to the overall count which is fairly satisfying.

Some of the moths identified in 2016 include the Female Ghost Moth (left) and the Coxcombe Prominent Moth (right).

Female Ghost Moth (left) and Coxcombe Prominent Moth (right) (744)

The data in the 'core' species list (see below) has been colour coded in 'traffic signal' style to indicate 'red' for those species that were absent 'yellow' for those species who's numbers remained the same and 'green' for those showing an increase. The yellow shaded area at the bottom of the list contains the new species (8 in total) which were not identified in preceding years (not because they were not present in previous years but because I have had more time to sharpen my id skills). Surveys focus on the 'core' list from 2008 but as before I remain on the lookout for any species that don't look familiar in order to add them to the Highdown Species list total which now stands at 189 species to the end of 2016.

PDF FileHighdown Gardens - Moth species list 2008 to 2016 (130KB)

So far, it has been a rather interesting year for migrant moths. A very large influx of 'diamond back' moths were seen in the Gardens and all over Sussex during the summer. This species originally believed to have originated form the Mediterranean region has now spread worldwide and is able to migrate large distances during favourable conditions. As well as being rather small it is able to re-produce very quickly and in huge numbers. It has now occupied every continent except for Antarctica and can be a serious pest in crop fields of oilseed rape and cabbage.

Convolvulus Hawk Moth (340)

Other migrant moths are less formidable and rather more attractive and include the Convolvulus Hawk Moth, one of which was captured in the Gardens in early September (see photo).

Persistent Southerly winds always bring the best migration results and Highdown Gardens is very well placed to monitor movement. Migrant moths crossing the sea will land and rest when they reach land. They may also be attracted by lights from shipping and enjoy the free lift to reach foreign shores although the 80 mile crossing from France is of no challenge to a small moth at 10,000 feet being blown along in a steady 40mph wind. Add to that its 15mph flight speed! It's easy to understand how they are able to travel large distances in a relatively short time. The Convolvulus Hawk is a true master of this and has a normal flight speed of 35 to 40mph! With wind assistance that's 80mph ground speed when at altitude and rather faster than the ferry!

Once again I would like to thank Jo Hooper, Highdown Gardens' Manager and Head Gardener, and Worthing Borough Council for their kind permission to carry out this exercise and I very much look forward to the ongoing survey.

Richard Poxon

See also photos of wildlife at Highdown Gardens

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