Observations

245

NOTES ON REARING LEPIDOPTERA

markings, and then red marks appeared, leaving almost circular cream areas scattered all over the surface. T h e larvae started to hatch on 8th June, and were fed on birch ; when first hatched and seen under a magnifying glass, they had a curious translucent appearance, which lessened somewhat after they had been eating for a few days. In the later instars, except the last, the resemblance of the larva to a bird's dropping on the leaf was remarkable ; the middle segments were dark brown with the head and tail ends white.

When not eating the larvae always rested in a curled-up position in the form of an interrogation mark. There was a number of long spines on the body, thickened at the ends. After the last moult the appearance of the larvae changed completely ; the resemblance to a bird's dropping was lost, and each segment was marked with a broad yellow bar, making the larvae now verv conspicuous. The long clubbed spines were very prominent, and together with the yellow and black markings served to give the larva a most remarkable appearance. The rearing of the larvae was very easy, and they were fed all the time on birch.

On one of the larvae the yellow bars on two adjacent segments were joined ; this larva was segregated from the others, and an attempt will be made next year to obtain a pairing between the resulting moth and one of the others, in order to determine whether the abnormal marking is inherited. When the larvae were fully grown, rotten wood and short hollow stems were provided, and the larvae soon disappeared into the stems or into the rotten wood for pupation.

S.

BEAUFOY.

OBSERVATIONS PEARL-BORDERED FRITILLARY (Argynnis euphrosyne Linn.).

At the edge of Belstead Wood this butterfly is always to be seen at the correct time of the year, but usually only in small numbers.

This last spring, however, they were there in profusion, feeding upon the flowers of bĂźgle.

D U K E OF BURGUNDY FRITILLARY (Hamearis lucina Linn.).

The larvae of this butterfly feed upon the leaves of primrose and of cowslip, but usually prefer the latter. As there was a remarkable increase in the number of cowslips this last spring, possibly due to the absence of rabbits, the Duke of Burgundy Fritillary may be seen in Suffolk again. It has not been reported for many years, but it is possible that it is still here in very small numbers, and that the increase in cowslips may cause an increase in the butterflies.

Will members interested please keep a sharp look-out for the species in May and June in woods where the cowslip grows ?

246

OBSERVATIONS

SMALL and ESSEX SKIPPERS (Thymelicus sylvestris Poda and T. lineola Ochs.). These two butterflies are always common in Suffolk, particularly the former, but it was noticed this last summer that there were considerably more than usual. Here again it is possible that the absence of rabbits may have been the indirect cause, as the favourite foodplant of the larvae, the cat's tail grass (.Phleum pratense) was left to grow without disturbance.

S.

BEAUFOY.

SOME OBSERVATIONS ON THE LIFE AND HABITS OF THE COMMON DIGGER WASP Oxybelus uniglumis Linn.

I have occasionally found these small black and white solitary females excavating their nests near to each other in a disused gravel pit at Bury St. Edmunds, usually in sand brought down at the pit face by the action of the weather. When excavating, as in all their movements, they were extremely quick ; usually one or more shallow nest-holes were excavated before a permanent site was selected. They dug rapidly into the sand with the forefeet, the sand passing under the body in a continuous stream as they quickly disappeared. The entrance became blocked and remained so throughout, only the damp sand which was occasionally pushed out gave the position. Dßring this work an occasional rest was taken, and on returning to the surface they spent some time exercising the wings and in making a survey of the surroundings. When the required depth had been reached, they returned to the surface, and the entrance was immediately sealed ; this was meticulously carried out by scraping the loose sand with the forefeet, the sand passing under the body back towards the nest in short stages. When sufficient had been deposited the work of Welling commenced : this was performed by running over it in various directions—the mid- and hind-legs appeared to be spread and dragged, frequently resting flatly and directly over it.

When completed, it could only then be located by some mark such as a stone or a dried grass bent. On the completion of this work the bearings for homings were taken, at first by short and then longer flights, back and forth at various angles around the nest.

Each time the wasps returned, they rested flatly over it. When returning from the longer flights they usually alighted a short distance away, completing the journey by running over the sandy floor, occasionally resting and appearing to note every plant and stone by the way.