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NEWSLETTER No. 9 -  Summer 1983

WEST MIDLANDS BRANCH, BUTTERFLY CONSERVATION

 

The Search for the Large Tortoiseshell In Worcestershire

The Large Tortoiseshell is now a very rare butterfly in the U.K. although in Victorian times it was not uncommon in some parts of the country, including Worcestershire. It is arguably the most elusive of all British butterflies. The intriguing possibility is that it may still be breeding in the county, and the best prospective area now seems to be the district to the west and north of the Malvern Hills.

The distribution maps of the Biological Records Centre show widely scattered plots over the whole country, strongly indicating a migrant species from the continent. One school of thought is that it is really a migrant that occasionally establishes itself in particular localities for a year or two. Almost all the records are of single butterflies though, and one wonders why more aren't seen in such localities. The answer may lie in its habits.

Observation is particularly difficult because it is essentially a tree-top dweller in the manner of the Purple Emperor, rarely descending to ground level. The difficulty is increased by the paucity of information on the best dates to look for the butterfly, also because there are hardly any pointers as to where to go. It really is a "needle in a haystack" situation. The butterfly probably hatches in late July or early August and appears to go into hibernation after a few days, emerging again in the following Spring to mate. The literature says that it is more likely to be seen in the Springtime. 

In the past, the tops of tall Common Elm trees provided the main breeding places, but these have all gone through Dutch Elm disease. The species will breed on several other types of tree, and Sallow and Wild Cherry in particular would now seem to offer the best prospects. These would have to be in sheltered but sunny locations, probably best in valleys where there are nearby streams and a fairly large proportion of woodland, or in low lying areas where there are several separate woods. The area between the Malvern Hills and Suckley Hills, then northwards into the Teme Valley, meets these requirements. What is now needed is an increase in the activity of searching.

Nearly all claimed sightings pose the question of possible mistaken identity, but I can quote five in this area of Worcestershire in the last 16 years which all seem probably correct:

The 1899 Malvern catalogue said "chiefly found, in this neighbourhood, about Mathon and Cradley, but occasionally elsewhere. Rather rare." (GR. 734458 and 735473). In the 1920's it was found along the Purlieu Way e.g. GR. 763442.

What is now wanted is one proven sighting, and members of the BBCS are ideally qualified to undertake the search. 1982 was a good year generally for butterflies and we had an almost certain sighting of a Large Tortoiseshell at Longley Green. The Spring of 1983 offers a  good chance. There can be no guarantee of success, but if the species could be found it would be a most creditable achievement for the West Midlands branch of the BBCS. If you can fit in a trip to the area do take a camera and a pair of binoculars.

Jack Green

*See Summer Programme for details of a Large Tortoiseshell hunt planned for this Spring.