2002 is to be a special year for finding the haunts of the White-letter Hairstreak;
here is how to go about it.
Hairstreaks are not found by chance; it takes a good deal of patience, not to mention planning, and a bit of luck! Knowing that 5 years of Millennium survey had not unearthed any new colonies of White-letter Hairstreaks in Suffolk, I decided to look harder in 2000. All I accomplished was to identify a couple of spots where suitable elms were to be found in squares adjacent to known colonies. I spent a lot of bent neck time, though, without actually seeing any, despite correct timing, good weather, and patient observation.
2001, by contrast, brought success, and has been White-letter Hairstreak year. Either the butterflies have had a really good year, or I have got the knack of it! During July, I found 3 fresh sites myself, and I know of at least 5 more found by Richard Stewart and others. Here is how to go about finding some for yourself.
The first move is to visit a known site in perfect weather in order to see what they look like, and how they behave. Ideally, get a friend to show you, as the colonies are very precisely situated. Take binoculars and a folding chair, and go in the first days of July, to leave the rest of the month for the hunt.
The potential sites will need to be sorted out by looking at the elm growth in the general areas where they have been recorded in the past. Consult Howard Mendel's book for pre 1986 records, and Richard Stewart's book for the sites recorded during 1995-99. The place you are looking for has good shelter, is probably off the road, and has elm suckers growing to a height of about 15ft. It may be a site that used to have mature elms before Dutch elm disease struck, and the presence of some diseased elm growth does not rule it out. A clearing at the edge of a copse with plenty of elm re-growth is ideal, particularly if there is bramble in the undergrowth, as a source of nectar.
Look at your diary for July, and make as many dates available for the search as you can. Poor weather and other commitments can gobble up the opportunities all too quickly. Once you know that the WLH is on the wing, it is time to get around your potential sites. If a heatwave comes along, you must resist the temptation to lie at home in a deckchair, as the most successful days are the scorchers. The butterflies sit in the sun on leaves towards the top of the elms, sometimes resting, sometimes walking about in search of their principal refreshment, honeydew left by aphids, and fly only rarely. When disturbed, or in pursuit of another insect, they lift off into a short chase, particularly if they find another WLH. At this height, they are difficult to spot, and can not be identified with certainty unless they are obliging enough to settle where you can get the binoculars on them. In flight, they are rather drab, less noticeable than a Purple Hairstreak, and rather smaller than the smallest of the Ringlets that do quite often get up into trees. You may well see Speckled Woods and Holly Blues flying amongst the trees, and these need to be firmly identified, although once you have seen the real thing, you are unlikely to confuse WLH with these species. On the other hand, if you are near oaks, do beware of the Purple Hairstreaks, which do settle in elms, and have the same distinctive profile on a leaf.
Your best chance of a positive sighting comes when the WLH come down to take nectar, as a change from honeydew. This can occur as early as 10am on a hot day, unlike the Purple Hairstreaks, that usually leave it until tea-time. So, what you have to look for is bramble or privet, flowering in the sun, under the elms. Very often, this dictates which side of the copse or hedge line you have to search. This can put your feet amongst the nettles as you close in to search the bramble patch. And you will need to search quite methodically, as a bramble patch is an excellent hiding-place. First you will spot the Whites, and then any Peacocks, Red Admirals, or Commas. On closer inspection, you will begin to find the surprisingly large number of Meadow Browns and Gatekeepers moving from blossom to blossom. If you do not, then you have got the wrong bramble patch - the one you are looking for is usually very popular, in a sheltered glade, and catching the full sun. Keep looking until you have found all the Holly Blues and Skippers that were out of sight behind the blossoms, and then hunt down all the bumblebees and hoverflies and malformed berries and twigs that can conceal the muted brown of the stationary head-on WLH just a yard from your face.
After that, it is a joy. The WLH will turn to get at another blossom, and you will get a broadside view of the hairstreak shape, the white line itself, and the orange markings above the tails. It may remain on the same blossom for 5 minutes, then fly six inches to the next flowerhead, and may still be there when you get back with the camera ten minutes later. If you find a decent colony, there will be more nearby. I found 6 in one glade near Cavenham, and 5 spread out along 400m of hedgerow, but there are accounts of other people finding 50 at one spot. Now is the time you get to see them flitting off to settle in the branches, and to become familiar with their "jizz"; after which it becomes easier to be confident about the next sighting. Most of their colonies are stable, so you can re-visit next year - on your way to the next prospective site, of course.
When you do your search for suitable-looking spots, why not go in May or June, at the time the larvae are feeding up. I'm told they are not too difficult to find by looking up through the leaves towards the sunlight. Part eaten leaves are a clue, but there are plenty of moths whose caterpillars feed on elm, so do not get too excited if they are long and thin, instead of the characteristic "slug" shape of the hairstreak caterpillars. Perhaps 2002 will be my year for finding WLH larvae!
If you do succeed, do remember to send your records to the County Butterfly Recorder, as 2002 is to be a special search for this delightful species. Good Hunting!
Rob Parker
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