Rearing the Monarch Butterfly (Danaus plexippus) in Suffolk

REARING THE MONARCH BUTTERFLY PLEXIPPUS) IN SUFFOLK

(DANAUS

S . BEAUFOY

large, conspicuous butterfly is a native of North America, where annually large numbers migrate from the south of Canada to the southern parts of the United States. Here they hibernate in masses on trees until the spring, when a return journey northwards is made, ova being deposited on the way. The resultant butterflies join in the northward journey to Canada.

THIS

In 1870 the Monarch was first seen in Australia, where it is now common. Düring recent visits that my wife and I paid to our daughter we saw many of these lovely insects in our travels through New South Wales. On Christmas Eve, 1967, we stopped in a Clearing in the forest near Port Macquarie, and saw the complete life history of the species, ova, young and fully grown larvae, pupae, and the adult butterflies, displayed on the cotton bushes (Asclepias), which were plentiful along the edge of the gravel road—the leaves of many of the plants had been stripped by the larvae.

I did not have with me all my apparatus, but I was determined to complete a photographic life history. Accordingly I brought home a supply of Asclepias seeds and raised the plants quite easily in my greenhouse in Ipswich, so that an adequate supply of foodplant was available when, the following year, our daughter collected a number of ova and posted them and the leaves on which they had been deposited, by air mail. All the ova hatched during the four to five day flight, and there were twenty newly hatched larvae to be transferred to the "homegrown" Asclepias bushes. I had no difficulty in rearing them through to the butterfly stage; eventually sixteen perfect specimens emerged from the pupae. The ova are small for the size of the butterfly; they are pale yellow, conical in shape and have a large number of longitudinal keels. The larvae grew rapidly, spending only two or three days in each instar. The fully-grown larva is about 2\ inches long with yellow and black bands. Just behind the head are two long, black filaments and at the tail end a shorter pair.

In the first instar these filaments are absent, and they appear as small bumps in the second instar. They then become proportionately longer at each successive moult.

When the larva is fully grown it crawls around for a day or two before finally coming to rest at the spot chosen for pupation. It spins a thick päd of silk on the support and embeds its tail securely in the silk, then hangs head downwards, attached by the tail only. Pupation takes place in the course of a day or two. The pupa is very striking in appearance, bright green with gold and

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Black spots. The pupal stage lasts about three weeks, when the colour becomes darker, and the wing colours of the butterfly can be seen through the outer case. The two sexes are similar, deep brown with black veins—the wing span is 4 to 4 | inches. The main difference in appearance between them is that the male has a patch of black scent scales on one of the veins of the hind wings.

These scent scales are scattered over the female by the male preparatory to pairing.

Our butterflies were kept in a large cage surrounding the foodplant in the hope that pairings would take place, but none occurred.

Doubtless with such strong fliers it is necessary for the insects to fly around before mating.

At Christmas, 1970, on our second visit to Australia we visited the same spot and, although the Clearing was somewhat overgrown, it was still frequented by the Monarch, and we again saw plenty of them, including a male and female paired.

Specimens have occasionally been found in Great Britain, and it is thought that these have come across from North America on ships. The species cannot survive in the wild in this country as the foodplant Asclepias does not occur here.

S. Beaufoy, M.B.E., B.Sc.(Eng.), C. Eng., F.I.E.E., F.R.P.S., F.R.E.S., 98 Tuddenham Road, Ipswich, IP4 2SZ.