What does the caterpillar look like?
The caterpillars are very small (about 1mm) when they first emerge and pale-green with a relatively large head. They are similar in appearance – although bigger - through the first few
instars. They look similar to those of the small white. By the 5th and final instar they measure about 25mm and are bright green with tiny black points all over the body from which white hairs grow, and with a line of black and yellow “bulls-eye” breathing holes (spiracles) along each side. See the
UK Butterflies site for excellent photos of the instars.
What do the caterpillars eat?
Unlike the “cabbage whites” the green-veined caterpillars do not usually eat cultivated brassicas but rely on a wide variety of wild plants mostl
y in the Brassicaceae family such as watercress
Rorippa nasturtium-aquaticum, cuckooflower
Cardamine pratensis,
garlic mustard Alliaria petiolata, charlock
Sinapsis arvensis and hedge mustard
Sisymbrium officinale.
1.
What happens in winter?
Green-veined whites overwinter as pupae from the second brood, usually low down in vegetation.
Flowers they take nectar from
Adults feed primarily on betony, bluebells, bugle, buttercups, common fleabane, cuckooflower, greater stitchwort, hemp-agrimony, knapweeds, ragged-Robin, ragworts, red campion, thistles, vetches and wild marjoram. 2.
How are they doing?
The green-veined white appears to be declining slightly in both numbers and distribution – although still very widespread. The 2022 State of UK butterflies report shows a decrease in numbers of 14% since 1976 compared with a decrease of 7% in the 2015 version. The distribution has decreased by a statistically significant 11% over the same period whereas in 2015 it was reported as increasing slightly. However the report does not distinguish between sub-species (see below).
Other interesting facts
There are three sub-species of green-veined white in the UK. Pieris napi sabellicae is the sub-species in England and Wales; Pieris napi britannica in Ireland, and Scotland is lucky enough to have both these plus Pieris napi thomsoni. The latter two sub-species are generally thought to have brighter yellow underwings. The subspecies are pretty similar in appearance but britannica and thomsoni generally have brighter yellow underwings.2.
References
3. State of UK Butterflies 2022
report
Page written by Judy Skinner, reviewed and compiled by Steve Head