Friday, 6 May 2016

An Intriguing Tale of Moths and Cuckoos

23rd April 2016

The Brown-tail Moth (Euproctis chrysorrhoea) occurs in most of Europe but is predominantly an insect of southern coasts and estuaries in the UK, with only internal migrants occurring inland. The caterpillars have small hairs all over their bodies which can break off very easily and irritate the skin, in some cases severely. Some people can also suffer a type of asthmatic reaction.

The white adult moths have a wingspan of about 35mm and fly at night in July and August. The female lays her eggs on the stems of larval food plants (Blackthorn, Hawthorn, fruit trees) and covers them with a layer of irritating hairs from her abdomen. The eggs hatch in late August and the caterpillars immediately spin a silken tent over several leaves under which they shelter during dull or wet weather.

The caterpillars feed until October when they enter hibernation in the nests. They resume feeding the following April, before pupating in late June. The caterpillars are between 7mm and 38mm in length depending on age, and are dark brown in colour with a distinct white line down each side.

So what is the connection between the moths and the Cuckoos? Well, it is quite simple. Cuckoos arrive on the south coast just as the caterpillars are beginning to emerge, and the Cuckoos love them. So it is a great opportunity for them to gorge themselves before continuing their onward journey. One such infestation of Brown-tail moth nests is at Heybridge Basin and affects bushes, mainly Hawthorn, over an area the size of a football pitch. Despite Cuckoos being relatively scarce, I saw no less then eight individuals, all spending their time moving from one nest to another, which of course provided some excellent photo opportunities.

What an amazing morning.......and now on to Abberton.

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