Saturday, 16 June 2012

To Conserve and Protect! The Netted Carpet Moth and the Touch-Me-Not Balsam plant.

The strikingly patterned Netted Carpet Moth resting on an elder below which are growing many hundreds of touch-me not balsam plants at St. Catherine's. 
The Netted Carpet Moth (Eustroma reticulatum) is one of the rarest moths in the U.K; (reticulum is Latin for small net). The UK Biodiversity Action Plan (BAP) classes the moth as a priority species; it is listed as vulnerable in The Red Data Book.

Netted Carpet Moth on Balsam Leaf. Late July. Image courtesy of  John Knowler.
The moths lay their eggs singly on the plants in July and August.
It is vulnerable mainly because the moth larvae/caterpillars are entirely reliant on a scarce annual plant known as Touch Me Not Balsam (Impatiens noli-tangere). It is the caterpillars' only food source.

Both the moth and the plant, which is the only balsam native to the UK , are restricted almost exclusively to the Lake District, albeit in small numbers, and at just a few sites.

One such site is at St Catherine’s in the East Windermere area.

Netted Carpet Moth Caterpillar on Touch Me Not Balsam at St Catherine's. Late August. note partly eaten seed pod. Caterpillars will have pupated on the ground by October. Adult moths emerge in July and may be seen until mid August.
National Trust Rangers have greatly increased the numbers of plants here, and hence the annual moth populations over the years, by actively improving conditions for the plant.

Touch Me Not grows well in damp open woodlands, especially after the ground has been disturbed. Without regular ground disturbance - in Winter and or early Spring - plant colonies will decline, becoming overwhelmed by perennial species such as brambles and creeping buttercup. Severe ground disturbance and the pulling up of brambles are tasks undertaken by rangers and volunteers at St. Catherine's  before the seedlings appear. 

 A good stand of Touch Me Not Balsam at St Catherine's. Mid July 2011
Touch Me Not also requires dappled sunlight to grow well; some wooded areas are managed with this in mind; branches have been cut back, and a certain amount of coppicing takes place.

Touch Me Not Balsam seedling appearing in Spring. Millerground.
A bumble bee pollinating Touch Me Not Flower. Millerground Late July 2011
At Millerground, in 2009, the cutting down of non native trees has let in a lot more light. This has allowed touch me not plants to be reintroduced, and to thrive here once again after many years absence.

The annual Netted Carpet Moth Survey, that takes place in early September, has already recorded Netted Carpet Moth caterpillars to be present at this site which is very encouraging news.

A Netted Carpet Moth Caterpillar forming a triangle between leaf stem and stalk.
A Netted Carpet Moth Caterpillar munching on a seed pod!.......image courtesy of John Hooson.
Finally, invasive, non native Himalayan Balsam is pulled out regularly to prevent it from overwhelming and displacing the far less common and much less competitive or robust Touch Me Not Balsam stands.

Himalayan Balsam (pink flower) encroaching on Touch Me Not.
Pulled out shortly after photo was taken!

Roland Wicksteed: Central and East Lakes.


  1. Really interesting - thanks for the post

  2. So many moths have become extinct. Good to hear of more conservation. The Fisher's estuarine moth is also extremely rare and is only found in north east Essex. Its caterpillars are also restricted to a single food source, a plant called Hog's fennel.

  3. This is the third time I've been to your website. Thank you for explaining more details.
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    1. Thanks Andrew for your interest. Your thanks for the post that I put together is much appreciated.

      I "googled" the Fisher Estuarine 19th June comment; as stated it is very rare. Good to read that Colchester Zoo are very involved with a breeding programme to help boost numbers for this endangered moth.