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I took these pictures while on holiday in Bulgaria last year. I’ve always read that the Black Veined White lays eggs on the underside of the leaf, however as these pictures prove it, this is not always the case. The tree was a kind of prunus and I saw that other females (there were about 20 others at the time on the same tree) were doing the same. The eggs are very conspicuous but did not seem to be eaten or damaged by anything. I thought about it and wonder if with the eggs being exposed to the sun, they develop quicker or maybe there is a chemical substance which deters predators. … Does anybody know about this behaviour?
I have witnessed other Whites (large and small) laying eggs and it was always underneath the leaf.
Thanks for your comments.
Sylvie

Great observations, Sylvie!

I have seen Large White lay on the tops of leaves, but only when the leaf was bent downward (and, I assume, with the female thinking she was laying on the underside of the leaf).

Cheers,

- Pete

Hi Pete,
I have done some reading and apparently, the way the female Black Veined White lays her eggs depends greatly on the ambient temperature and the elevation of the site. At lower altitudes, the underside of the leaf is favoured because it tends to be warmer whereas at higher elevations the upperside is chosen.
The choice of the egg laying site also may be an indication that the temperature plays an important role, for instance eggs are laid on the north side of the food plants at lower altitudes and on the South side at higher altitudes.
Sylvie

Thanks for looking into this, Sylvie - absolutely fascinating!

Cheers,

- Pete