Barberry Carpet Moth, Second Report

BARBERRY CARPET MOTH Second Report C . W . PLERCE LAST year's appeal for help in assisting to build up a population of the Barberry Carpet Moth (Pareulype berberata Schiff.) met with no response. This is understandable, except for any entomologist living in the Bury St. Edmunds area. As far as is known, none of the food plant, the Wild Barberry (Berberis vulgata) is known to exist anywhere eise in the County and anyone wishing to undertake breeding of this species would have had to make many long journeys to get fresh food for the larvae. Indeed, between the date of the first emergence, 6th May, and the day on which I collected the last batch of Wild Barberry, eight visits were required to ensure the food being changed at least every other day. The number of visits would have been greater if I had not had one or two small bushes in my garden. Fortunately, as the result of some experiments with some varieties of cultivated barberry planned by Messrs.

Peter Wright, John Shackles, David Chipperfield, and myself, these visits should not be necessary next year.

Of the twelve pupae which went down last autumn, ten produced healthy imagines and one deformed and useless moth, the twelfth being totally dried up. DĂźring the winter the pupae had been kept in a cage in the open air, with protection only from mice and birds.

The first two moths, one of each sex, emerged at 1000 hours on 6th May and were put into a large cheese Container covered with butter muslin. To keep them alive as long as possible some fresh flowers and watered honey was placed in the Container, together with some wild barberry on which, it was hoped, the female would lay her eggs. Further emergences took place on 7th May (female), 8th May (two males), 9th (male), l l t h (female), 12th (two males), and 13th (male). Hence from the twelve pupae from last year, three females and seven males were obtained. There appeared to be no fixed period of the day in which emergence occurred. In two cases the newly emerged was seen at about 0700 hours with its wings already dried and the actual time when it left its pupa case could not be determined.

The other two females were put into separate cheese Containers, each with two males. The other two males were kept in reserve for possible mating with any further females which, it was hoped, would be obtained in the wild.

The first May, exactly on l l t h May A surprising

pair were found in cop. at 2200 hours on 7th 36 hours after emergence. The female started to lay and continued to do so until her death on 23rd May. event occurred on 8th when this pair copulated for

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the second time, possibly because of the lack of successful impregnation the first time. Altogether this female laid about 200 eggs.

Because hatching was imminent, Shakers Lane was visited on 14th May to obtain some fresh wild barberry. It was also hoped that some more moths could be caught for breeding. None were seen, but some eggs were found on the food plant, which were found later to be those of the Scarce Tissue (Rheumaptera cervinalis Scop.). This moth also feeds on barberry, but unlike berberata is single brooded only. Larvae of this species were noted on food plant collected on subsequent occasions. It is possible that this species, as well as other insects, is necessary for the continuance of berberata in its ecological niche and some thought should be given to this fact in establishing a new colony. The same applies to the whole plant association of the Shakers Lane hedgerow.

T h e second female mated on 9th and started laying on 12th.

On 25th May she was put into a second Container with another male, after having finished laying. She mated for the second time and continued laying, but it is not possible to be certain if the latter eggs were the result of this second mating, although the indications are that it must be.

T h e third female was seen in cop. on 12th May and was laying eggs by the 14th.

Another visit to Shakers Lane resulted in the capture of a female, which was put with one of the so far unmated males. Egg laying followed, but the identity of the male parent is uncertain as she may have mated before capture. This was not the case with a second female taken on a visit to Bury on Ist June. She was left on her own for two days, but as no ova resulted, she was put with the last of the unmated males. By 6th June she was laying.

Over 1,000 eggs were laid between l l t h May and 17th June, of which about 600 were laid by the three females descended from the 1970 larvae and about 400 by the two captured this year.

As the infantile mortality appeared to be the same as last year, i.e., about 80%, it was to be expected that about 200 pupae should have been bred through this year. However, some losses occurred among the half-grown larvae through their being eaten by diptera larvae, obviously gathered with the food plant. When these were looked for carefully, the losses were far less although some of these predators did escape notice. The practice of changing the food daily, although laborious, reduced the losses considerably.

T o return to the larvae, by l l t h June four had pupated, having been in the larval State for twenty-two days, which tallies with the time taken by last year's larvae. Pupating continued and by 4th July there were seventy-two pupae and twenty-three larvae. The moths then started to come off at least four weeks before the

513 expected time. As I had to go away the next day for a week and with Peter Wright abroad at this time, I had no option but to put all the stock into the breeding cages withflowers,watered honey, and food plant. The cages were put in a shady part of the garden.

On my return I could see that more imagines had appeared and several pairs had mated, but it was impossible to determine the proportion of the sexes. John Shackles of the Nature Conservancy, in Peter Wright's absence, took all the imagines and released them in Shakers Lane, as the plants in the Forestry Commission's plantations had not grown sufficiently to support a colony of moths. Indeed, it was now feit that a mistake had been made in choosing this site and that future plantings should be carried out nearer to Bury St. Edmunds. It was also thought that it was better to strengthen the existing numerically weak population in Shakers Lane, so that, by 1972 when new plantings had been made, more moths could be taken from there and bred for release in these new areas.

Peter Wright called on 20th July and took away most of the remaining imagines and pupae for release in Shakers Lane, leaving sufficient ova with which he, David Chipperfield, and I could conduct experiments with cultivated barberry so that moths could be bred far away from Bury. This would enable more entomologists and others to assist in building up a larger viable population.

In the meantime efforts were to be made to get larger quantities of wild barberry propagated and planted in more suitable habitats.

It was agreed that Peter Wright would try to bring through P. berberata on Berberis vulgata var. atropurpurea, David Chipp would try B. darwinii, and that I should try B. stenophila. B. thunbergii, and Mahonia aqidfolia.

Both Peter Wright and David Chipperfield were successful and bred several pupae on the plants chosen, but I had success only on B. thunbergii. While half-grown larvae would eat Mahonia, no freshly emerged larvae did so. Some of the larvae of all ages fed for a few days on B. stenophila, but 60% died within three days and because of the small number available, it was decided to concentrate on B. thunbergii on which so few died. One very important fact emerged from these experiments, namely there was less mortality amongst the older larvae than when fed on the wild barberry, this being due entirely to the absence of predators on the cultivated plants.

After Peter Wright took away the remaining moths in mid-July, there remained about eighty eggs on the food plant. Twenty were used for experiments on Mahonia and stenophila and from the remaining sixty, twenty-eight pupae developed. This is a far higher percentage than that obtained both with thefirstbrood of this year BARBERRY CARPET MOTH

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and with the autumn brood of 1970. There are now twenty-seven pupae remaining from the batch fed on stenophila, one male of the third brood having come off on 13th September.

Reference Pierce, C. W . (1970).

15, 273.

Barberry Carpet M o t h .

Suffolk

Natural

C. W. Pierce, 14 Chalkeith Road, Needham Market,

History

Suffolk.