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Suffolk Natural History, Vol. 41 Egg for Breakfast
It was May, 2005, and a small plant of honesty was growing among my vegetables. As I removed it I checked it carefully for eggs of the Orange-tip butterfly (Anthocaris cardamines L.) for it sometimes lays on honesty instead of the more usual garlic-mustard. Usually, if eggs are found at all, there is only one. They are bright yellow, and so are quite easy to see, attached to the stalks just below the flowers. This plant had two sprays of flowers, and I was surprised to find an egg on one spray, and two on the other. So the separate sprays were placed in a jar on my window-sill. It is well known that the caterpillars of the Orange-tip are cannibals, and must be reared separately. Once, in 1968, I watched a “fight” between to almost fully grown larvae, which I described in S.N.S. Transactions Vol. 14, Part 3, pages 212–213. I have often suspected that “disappearances” could be explained by larvae who roamed too freely. In this case one egg looked reasonably safe, but the other two would need watching. The eggs, when first laid, are pale green, but turn yellow after a day or two. In a week or two they turn drab-coloured as the larva within, in “horseshoe” mode, show through the transparent shell. Then it bites its way free and (like most other butterfly larvae) nibbles about half the shell for its first meal. This leaves a transparent “basin” attached to the plant. It was not convenient to separate two eggs laid less than a centimetre apart. That they had been laid by different females became apparent when one turned brown first a, and then hatched. It was harder to find the tiny 2 mm larva among the big honesty flowers than would have been the case on dainty garlicmustard, but eventually I did find it very close to the second egg, which had now turned brown. With some difficulty I managed to get it into view under low power on my microscope. This more or less confirmed what I had suspected – it was having “egg for breakfast”. The pale greenish-yellow caterpillar had a black head, black legs, and was covered with black spots – each sprouting a hair with a bead of liquid at its tip. The “second” egg appeared half-eaten, drab-coloured, and with a few black spots with hairs inside – remains of the victim. Another “hatched” egg, under the microscope, was a dainty, empty transparent bowl. So the second mum should really have been more vigilant when she laid her egg. Wilfrid S. George 43 Linden Road Aldeburgh Suffolk
IP15 5JH.
Trans. Suffolk Nat. Soc. 41 (2005)