The Essex Emerald moth is one that could be mistaken for a butterfly in shape. The invertebrates_freshwater
Essex emerald moth biology
The Essex Emerald moth is on the wing from mid-June to early July, but has not often been found as the adult insect. The eggs are laid on high invertebrates_freshwater
The caterpillars, on hatching, cover themselves in pieces of the foodplant, presumably as daytime camouflage against predators. They feed at night and are able to survive inundation by salt water during high tides. The caterpillars hibernate over winter and resume feeding on sea wormwood in spring. By the end of May they are fully-grown and pinvertebrates_freshwater
The Essex Emerald moth is recognised as a subspecies of Thetidia smaragdaria, which has a much wider distribution, ranging across most of Europe from southern Scandinavia to the Mediterranean, and eastwards to Siberia, northern China and Amur, to Japan. In the UK, Thetidia smaragdaria maritima was last found only around the coastlines of Essex and Kent.
This moth has now been declared extinct in the UK, and the nominate species found in Europe and Asia has also declined to the point where none have been seen in recent years. Factors that may have contributed to the disappearance of this moth include: a loss of habitat through inappropriate grazing, unnecessary removal of vegetation including the foodplant plus fires along sea walls; coastal development together with re-building and maintenance of seawalls as well as agricultural improvements adjacent to sites; and finally, genetic instability due to the inbreeding of a small captive population.
The Essex Emerald moth is still listed in the UK Biodiversity Action Plan, and included in English Nature's Species Recovery Programme. The last known site for the species was monitored each year until 1993. Although a captive-breeding population survived until 1996, and five re-introduction attempts have been made, it is feared this moth is now extinct in the UK.
Any future plans for this species rely on a hitherto unknown population being found and protected. At the present time, none have appeared but the search will continue in the hope that this attractive insect might once again be included in the list of British wildlife.
The UK Biodiversity Action Plan for this species is available at UK BAP.
This information is awaiting authentication by a species expert, and will be invertebrates_freshwater
Hibernation is a winter survival strategy characteristic of some mammals in which an animal’s metabolic rate slows down and a state of deep sleep is attained. Whilst hibernating, animals survive on stored reserves of fat that they have accumulated in summer. In insects, the correct term for hibernation is ‘diapause’, a temporary pause in development and growth. Any stage of the lifecycle (eggs, larvae, pinvertebrates_freshwater
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