Orange Tip

(Anthocharis cardamines)

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The male is impossible to confuse with any other British butterfly: the orange tips warn of an unpalatable taste	The orange tip is also present on the upper part of the male's underwing, the lower part of which is beautifully marbled	The male pictured here must have only just emerged, as he was quite happy to have his wings stroked and to perch on our fingers!
In flight, or with wings open, the female very much resembles a Small White. The white spots on the edge of the wing-tip tell them apart	Once settled with wings closed, the marbled underwing, a camouflage defence possessed by both sexes, resolves any doubt	The full underwing is shown here, on a female laying eggs. She moves from plant to plant, laying and also feeding from the flowers. Note the egg on the stem below her
Egg-laying requires mating of course, as in the case of these two pairs - the first on meadow grass, the second on the more preferred garlic mustard		The eggs are laid singly on plants of the crucifer family, most often on garlic mustard (alliaria petiolata), and are initially white
The eggs turn orange within a few days of being laid though, which makes them easy to find	A different egg, showing the usual position just below a full garlic mustard flower-head	There is usually only one egg per stem as the caterpillars are cannabalistic! Trouble in store here, methinks
Once it is known where eggs were laid, the caterpillar is easy to find after hatching despite being well camouflaged (and initially very small!)	The caterpillars grow quite quickly - this is just a week later	After a further week feeding on the seed-pods they are very easy to spot but are not eaten by birds due to their unpalatable taste
As mentioned above, eggs are also laid on other plants of the crucifer family. This caterpillar is on honesty (lunaria annua)	The caterpillars move off the food plant after about 25 days in order to pupate in vegetation. This makes the chrysalis very difficult to find - I must confess that these two are from caterpillars we raised at home! Amazingly, this stage lasts for 10 to 11 months

Most caterpillars we raised had already fallen victim to parasites though, and thus failed to pupate. One which survived formed a chrysalis directly on the wall of the container we had put it in, which we transferred to the garage to over-winter. We brought it back into the house in early spring and were delighted to find that a butterfly soon emerged! And if you are wondering how a butterfly that large can come out of a chrysalis that small, the answer is that the wings only get "pumped up" (with blood) after emergence. The second image show the chrysalis case, below it the fluid expelled during emergence, and to the right excess blood expelled during wing inflation

We released her outside, and after an uncertain walk up the garden wall she transferred to a branch, showing the fully-black wingtip which identifies her as female		We saw her on several days thereafter, and so it was that our first orange tip of the year was female, rather than the expected male, and a fortnight too early!
We gathered about a dozen chrysalis late in 2020, some from caterpillars and some found on garlic mustard. Many of these were parasitised but we had 5 "hatchings" in spring 2021 - one male and four females. This is the male just after emergence and sitting on a sprig of mahonia inside the net we use to observe them before release		Interestingly, when seen against the light (not often the case in the wild), the marbled underside of the wings shows through to the top surface

In order to further investigate the parasite problem mentioned above, in summer 2021 we instituted a programme of collection of caterpillars, observation of the outcome and recording of the results. This will of course have to continue until spring 2022, when we will see what the emergence success is, but it has already provided us with a chance to observe the pupation process at close quarters.

In preparation for pupation, this caterpillar has attached its "tail" to the garlic mustard stalk and is hanging from it supported by a thin filament which is just visible in the enlarged image. While it appears to have a "face" at the upper end, this is just an illusion created by the fortuitous coming-together of several claspers and a white marking. At the right is the situation the next day. The upper part of the caterpillar has bent backwards and transformed into the main volume of the chrysalis while the skin has become a protective shell - bright green initially but becoming brown after a few days
And this is an example of what can go wrong. At the left is shown a now-empty chrysalis case attached the the side of the box we use to hold each caterpillar, with a brown rugby-ball shaped object beneath it - shown in close-up on the right. This is in fact the pupa of the parasite which had invaded the chrysalis. The parasite actually emerges as a grub but very quickly pupates and so we did not see any in the grub state. As part of the study we sent a couple of pupae to an expert on parasitic flies who allowed them to emerge and identified them as tachynids, probably a species of the genus Phryxe.

More results next year!