If you watch birds for long enough over the years you come to know many species without really looking at them, there is just something that you know is characteristic of that species. A word was coined to sum that up - jizz; it just is! The jizz of a species is not confined to birds though, it can apply to insects too, even plants to a degree!
One such insect is the orange-tip butterfly (Anthocharis cardamines). If you watch them carefully you will notice that they have a very skittish flight. I can not find a suitable way to describe it, but take a look and I think you will see what I mean. Other white butterflies tend to have a very direct flight.
The male orange-tip is very distinctive and cannot be confused with anything else but the female lacks the orange tips to its wings, instead the tips are black and so it can be mistaken for a small white (although small whites fly later in the year, usually after the orange-tip has finished). At rest you can see the beautiful marbled pattern on the underside of the wing of both sexes which is unique to this species.
Orange-tip butterflies emerge in early April for another season. Sadly, in my view, they only have one brood a year and we see them for just a short period of about six weeks each spring. It has two main food plants for laying its eggs on, both of which come in to flower at the same time as the adult orange-tip emerges. The first is garlic mustard (also known as Jack-by-the-hedge) and the other is cuckooflower (or lady's smock). As a result, the best place to see orange-tips is along woodland edges, hedgerows or damp, marshy pasture. Passage insects will often fly through gardens too.
The orange-tip is a primarily a southern species of butterfly and is quite common in Dorset.