Cheshire Macro-Moth Papers - Paper 6

Putting Sex Into Square-Bashing:

When Geoff Hulme found a Vapourer Moth (Orgyia antiqua L.) cocoon in his garden in Wilmslow with the female still laying on it I realised that this could provide the means to record the Vapourer from most of the squares from which it was 'missing'. It had been recorded from the Wilmslow square (SJ88) and most of the adjoining squares, but not from SJ44, 64, 67, 68, 76, 86 or 99, many of which are well worked squares with a resident recorder.

My idea was based on some of the unusual features of this species. The female is wingless and never leaves the cocoon where it lays all its eggs and dies. When nearly full-fed the larvae of the male can be distinguished from those of the female. They will feed on a wide variety of trees and shrubs and tend to occur in gardens and parks and even really urban areas. The male flies mainly by day but is not easily netted so although seen may not be recorded with any confidence; records are more likely to be of larvae found in the garden.

The plan was to locate/place two or three female cocoons in a garden in each of the squares where records are still needed. If the garden owner keeps a fairly close watch it is likely that a visiting male will be seen. Even if one is not seen, if the eggs are laid and prove fertile the presence of a male is proved! The cocoons were ready for distribution at the beginning of August and females began hatching almost at once with quite dramatic results. Two lots were sent out by post but the rest I took out and suggested locations for the cocoons.

On the morning of Thursday the 4th I took three to Eric Thurston in Hartford (SJ67), one of the three had already hatched; by the time I got home Eric had been on the 'phone reporting the arrival of a male! After lunch I took another batch to Tom Davison in Buglawton (SJ86), a slightly shorter journey, so that I just managed to get home again before Tom 'phoned to report the arrival of a male. The next day Anne Kearsley 'phoned from Gee Cross (SJ99) to say that two of the females had hatched from the cocoons sent by post and that they had both attracted males on the fourth and had started laying eggs on the fifth.

As Rob Wynne at Malpas (SJ44) was away on holiday until the 7th, I took three of the last to pupate down to him on the afternoon of the 8th, and he actually observed the arrival of a male the next morning in bright sunshine, and he was able to watch it circle round while locating the female. We thus had positive records of the Vapourer in four new squares. In the remaining three the females hatched and duly laid good batches of eggs but as males were not seen we must wait until 1995 for proof that males were flying in those squares. We wait with considerable confidence because I have noticed in captivity that if a female is unmated she will lay eggs but sporadically and untidily. It was not surprising either that not all my helpers were able to see a male as those who did noticed that the male only stayed with the female for about a quarter of an hour, a much shorter period than many moths spend mating.

An interesting by-product of this experiment was a strong indication as to where the name 'Vapourer' originated. When the young larvae hatched from the eggs they showed no interest in food but had the urge to climb upwards as much as they could and to produce silk-threads which readily caught in the wind. In effect the colony of young larvae evapourated !!

C. Ian Rutherford.
September 1994












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