On July 17th 2003 I spent the day recording beetles in Glemham Park, Little Glemham (TM 3459). It was a day of warm sunshine and many butterflies were in evidence, in particular, large numbers of the Painted Lady (Cynthia cardui L.) on teasel heads. As I headed towards a large mature oak with a straight trunk devoid of branches for the first twelve feet or so I became aware of what I initially thought were leaves drifting around the trunk at about head height or above. Approaching closer, I realised these “leaves” were Red Admirals (Vanessa atlantaL.) and, upon going to the previously hidden side of the tree I realised the reason for their presence. A sap run some 10ft long ran down the trunk, probably as a result of a lightning strike, with the bark on either side of the fissure “weeping” and only loosely adpressed. Some 25 Red Admirals were imbibing the sap at any one time with several others at all times circling round the tree trunk. Many wasps (Vespula sp.) were also partaking of the feast and a pair of hornets (Vespa crabro L.) was intent on capturing butterflies; severed wings below the sap run indicated their previous successes.
In my experience, such extensive sap runs are relatively uncommon. Sap runs are of particular interest to a coleopterist as they often attract species that are rarely taken in any other way. The Red Admiral is a well-known imbiber of sap and the fermenting juices of over-ripe fruit.
Our founder Claude Morley wrote of the rarity of finding a recently lightning-damaged oak in 1936 (Trans. Suffolk Nat. Soc. 3: 79- 180, including photograph) and his observations are worth repeating in the context of this note:
“The Riven Oak – This popular feature of legends, recalling Hern the Hunter and Queen Bess stag-shooting in Heveningham Park, is neither rare nor conspicuous when toned to normal colour by atmospheric influences; but a quite fresh rive is certainly a singular object. I never witnessed one till 26 September last and, when come upon, such a scar is not a thing to go unseen, for the pale cambium-layer and but slightly darker inner bark stood forth with great prominence from the top of a straight and well grown young Oak of just about a century’s age right down to the ground, in strong contrast to the dull-ruddy remainder of the trunk. So fresh and moist was the white streak, averaging four inches broad, down the tree that it seemed sure to have been struck by the comparatively small thunderstorm of the 16th morning. No dryer were the long and narrow strips of bark, of varying length and breadth, which the lightning’s force had torn away and now lay in exact ratio to their size, the smaller close to the trunk and the larger further away, while the most considerable, a piece some six feet long by the full breadth of the scar had been dashed thirty feet across Westleton Heath.”
I thank Major Philip Hope-Cobbold for permission to record beetles in the park.
David Nash, 3 Church Lane, Brantham CO11 1PU
© 2003 Suffolk Naturalists' Society