Thursday, June 6, 2013
May-bug (in June)
This year seems to be a may-bug (aka cockchater) Melolontha melolontha year in Durham. This one flew into a computer store in Durham city centre. May-bug larvae spend several years feeding underground on roots before they hatch, so every three or four years large batches all mature together synchronously and hatch. They're attracted by lit windows at dusk and buzz around lights, in a way that can be quite alarming.
Adult may-bugs feed on plants. They're particular fond of tender young oak leaves and have been known to defoliate whole branches. In continental Europe they do a great deal of damage to orchards and orchard owners have been known to cover the ground between their trees with fine-mesh netting, to stop the adults emerging.
The 18th. century naturalist Gilbert White mentions periodic eruptions of may-bugs several times in his Journals, noting that when they appear hosts of rooks, crows and jackdaws feed on them. Here's a series of entries, revealing a four-year cycle of infestations:
May 26th. 1770
Chafers have not prevailed for some years now - they seldom abound oftener than once in three or four years. When they swarm so, they deface the trees and hedges.
June 30th. 1770
The Rooks pursue and catch the chafers as they flie, whole woods of oaks are stripped bare by the chafers.
December 1st. 1770
Some oaks have yet some green leaves. Those oaks that were eaten bare by the chafers leafed about midsummer and continued unusually green late into November.
May 17th. 1774.
Rooks bring out their young: they and the crows,and daws, and ravens, frequent the top of the hanger, and prey on chafers.
May 28th. 1774.
The crows, rooks, and daws in great numbers continue to devour the chafers on the hanger. was it not for those birds chafers would destroy everything.
May 19th. `775.
No chafers appear as yet: in those seasons that they abound they deface the foliage of the whole country, especially on the downs, where woods and hedges are scarce.
May 21st. 1778
Rooks bring out their young, after the chafers.
The saw-tooth pattern of white triangles underneath the wing cases is a distinctive ID feature.
The large, hemispherical eyes of may-bugs are particularly striking. This is a male, identifiable by its fan-shaped tips to its antenna (which are folded here).
The fine white hairs on the elytra of this specimen indicate that it has recently hatched - they quickly wear off as the insect ages.