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May butterflies and insects

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Put your cursor over any photo on this page to see its caption, or click here to see more May butterfly and insect photos. For more information on butterflies and moths see the Butterfly Conservation website.

May sees the overwintering butterflies - those that hibernated over the winter - giving way to others that are newly emerged. As a result the number of species on the wing increases but some of them are quite hard to spot.

Of the overwintering butterflies, small tortoiseshells once used to last into May but in recent years numbers have been shockingly reduced and in 2017 and 2018 none were evident after late April. Peacocks seem to be doing a bit better and can still be seen fairly regularly in the first half of May, with the occasional one, looking rather worn out by now, right till the end of the month. Both species look almost black in flight due to their dark underwing, but have a handy habit of landing for a rest on paths, making their colourful upperwings easy to see.

The striking yellow brimstone is more abundant and lasts longer, a common sight throughout May and with some lasting well into June. It is a "mobile" butterfly - that is, rather than defending a territory its males range widely across the countryside. For this reason they often fly past you in a hurry. Note that the female brimstone is a very pale yellow and can be mistaken for a large white butterfly: the key is its lack of black wingtips and the shape of its wing if you see it at rest.

Another overwintering butterfly is the comma, though it rarely seems to survive into May. You may just see it early in the month near bramble bushes and hedgerows, however. Also early in the month (all month in 2015 and 2016) you can see the lovely orange tip. Another "mobile" butterfly, it lasts as long as the flowers of garlic mustard, one of its favourite plants for laying eggs on. Again, the female can be mistaken for a small white butterfly as it does not have the orange tips to its wings: the key to identification is a mottled green pattern on its lower underwing.

You can only make this identification if the butterfly comes to rest, however, and that is a problem for all the other white butterflies, which seem to be especially restless. They are popularly grouped together as "cabbage whites" but there are in fact three different species - large white, small white and green-veined white. All three are on the wing this month but it is almost impossible to tell them apart as they flutter past. If you do see one at rest, then large whites have more extensive black wing tips, extending down the edge of the wing, while small whites have smaller grey tips.

Green-veined whites, meanwhile, have green stripes on the underside of their hindwing and their upperwings also have grey tips, but descending down edge in a series of blobs. For some reason they seem to make up a large proportion of the whites one manages to identify in May, but whether this is because they are more abundant at this time of year or just settle more often than the other two species, I do not know. All three species overwinter as pupae, though large and small whites also migrate from the continent in May.

Another butterfly that can overwinter as a pupa is the speckled wood, though some also spend the winter as caterpillars. This means they have less of a pronounced season than other butterflies and are reasonably well spread throughout May. If you see a brown butterfly in a wood or on a shady verge then it is almost certainly a speckled wood. They are relatively placid and happy to settle on a leaf, so are not hard to identify.

You may also see a red admiral or painted lady during May, though usually only a few individuals are around at this time of year. The red admirals are migrant females who have already mated on the continent and lay eggs here immediately on arrival, while the painted ladies mate once they arrive in the UK. In both cases, their offspring go on to make up a much more numerous summer generation, boosted by further migrants. Both species then travel back southwards in the autumn. Some red admirals also overwinter and survive into early spring but there is as yet no evidence that they go on to breed.

Rarer butterflies include the wall, which has brown on orange markings somewhat similar to those of the comma. Once a common butterfly on field edges, downland and railway lines, it is now only found on coasts (for example near Dover or on Portland Bill, with a more numerous colony on the ridge between Kimmeridge and Swyre Head near Swanage). It likes to sunbathe on paths (and also supposedly walls, hence its name) but is quite flighty when disturbed. Mid May onwards is also when the glanville fritillary can be found on downland and crumbling cliffs on the south coast of the Isle of Wight: some were also illegally introduced to Hutchinson's Bank near Addiscombe on the southern edge of London in 2011, where a few still survived in 2018.

Look out also for tiny blue butterflies during the month. Near brambles, ivy bushes or hedgerows early in the month (all month in 2018) these are likely to be holly blues, which have a pale blue underside and look a bit like a silver flash as they fly past. Later in the month and on grassland you may well be seeing the common blue, which can be distinguished by its brown underside with black spots.

Also later in the month, on south-facing downland slopes with horseshoe vetch growing, there is a possibility that you may be seeing an adonis blue - a fairly remote one as these are rare and localised butterflies, but one colony lives on the southern slopes of Ranmore Common near Dorking. Telling them apart from the common blue is a big challenge. The adonis is a lighter blue, but the common blue looks fairly light in flight too; the adonis has black lines through the tiny white borders on its wings, but the common blue has the beginnings of lines; the adonis blue male's underwing is darker than the male common blue's and with only the faintest of blue blushes near its body: and there are also slight differences in the arrangement of the black underwing spots between the two species. But unless you manage to take a good quality photograph you are unlikely to see these details. To make matters worse, when their markings fade adonis blues look a lot more like common blues.

The female of both these two species are brown with orange chevrons around the outside of the wing (practically invisible on the forewing of the adonis, but its female is very rarely seen). However, if you see a small butterfly with these markings, the brown argus is also possible. Its male is smaller than the female common blue but its female looks pretty identical. Again, the minute details of the black spots on the underwing are the guide to identification. Clearing up the confusion a bit is that you sometimes see common blue females whose upperwings are partly or substantially blue in colour: this is never true of the brown argus or adonis blue.

Also brown and very tiny - the smallest UK butterfly in fact - is the small blue, yet another butterfly of downland grassland (and yes, despite its name it is brown not blue). You really have to go to a site where they are known to be found in order to see them, and when you do their beige grey underwings are the key to identification. One colony is on the slopes of Pewley Down near Guildford.

Once you start looking for butterflies this small, all sorts of wonders open up. May is the best month to see both dingy skippers and grizzled skippers, but you might easily mistake these tiny brown-patterned butterflies for day-flying moths, so small and inconspicuous are they. Both are mainly found in downland or short, rough grassland (try the slopes of Pitstone Hill near Tring or the downland above Shere) but may crop up in other locations. Towards the very end of May you may also see the large skipper, a tiny orange butterfly that looks exactly like a moth, particularly in the way it folds its wings on landing.

Otherwise if you see a small orange butterfly it is likely to be a small copper or small heath. The small heath lives on grassland and is only ever found very close to the ground: it always closes its wings when it lands. The small copper is more adventurous and tends to crop up when one least expects it - on grassland, but also on flowery hillsides, even woodland rides.

One other very tiny butterfly, looking brown in flight, is the green hairstreak. It is fiendishly hard to spot due to its green underwing, which means it blends in with its downland habitat when at rest. Try Aldbury Nowers near Tring or the North Downs above Shere.

It is easy to mix all these small butterflies up with various tiny day-flying moths that are also on the wing in May. These include grass veneer moths, which look like tiny white butterflies as they flit around grassland but then close their wings tight to almost completely disappear when at rest on a blade of grass. On a slightly larger scale are brown moths such as the burnet companion and the mother shipton (both easily confused with the dingy skipper butterfly, as noted above).

Some day flying moths look for all the world like small butterflies - for example the fairly common speckled yellow, the white common carpet and silver-ground carpet moths, and - at the end of the month - the black chimney sweeper moth in meadows. Note also the very tiny micro moths, of which the small yellow underwing is one.


April has already seen quite a lot of tiny insects emerge (it is one reason those summer visiting birds come to our shores) and this continues into May.

One that used to be found in large swarms early in the month, but which sadly seems to have become rare in the south east in recent years (though 2018 was a reasonable year) is the St Mark's fly. Its legs trail below it as it flies, making it look rather sinister. But it is in fact quite harmless. Its name refers to the 25th of April, the feast of St Mark, when it traditionally appeared.

Otherwise, there are plenty of bees around - honeybees, solitary bees and also bumble bees. Solitary bees mate like any other insect and then the female lays eggs, with nectar for food, and seals them up until the larvae emerge as adults. Bumble bees are still queens earlier in the month. They mated in the late summer last year, hibernated fully-fertilised until March and then spent the early spring flying around look for nest sites. By the start of May their nests have been established and from around mid month the slightly smaller workers start to emerge. From this point on the queen never leaves the nest again; she essentially becomes a baby machine.

Other insects have evolved to look like bees for protection from predators - this is true of several species of hoverfly, which are by now to be seen everywhere (they can easily be distinguished from bees by their charming capacity to hover absolutely immobile in mid air). Notice also the bee fly, a fly that looks like a bee and is found more in the early part of the month. House flies (aka bluebottles) are also about but not a nuisance until later in the month, if then.

Instead, the kind of insect common in May are the tiny ones that fly into your mouth when you are running or cycling, or swarm at dusk, or produce mysterious insect bites on your arms and legs. Certain flowers attract them particular - look in buttercups or on the big white flowerheads of hogweed.

Ladybirds - particularly the common seven-spot ladybird - are mating in May: you can sometimes catch them in the act. Their larvae go on to feed on the late spring and early summer plant growth, with new adults emerging in the late summer to feed up and then hibernate. All sorts of other interesting insects are also evident if you look closely - bright red cardinal beetles (and lots of other beetle types), green shield bugs emerging from hibernation to lay their eggs, pondskaters on still water, crane flies in grassy fields - a whole insect ecosystem that we do not usually notice.

As the month goes on you can also see dragonflies and damselflies, including the beautiful banded demoiselle with its hypnotically patterned double wings. Look for the latter jockeying for the best position on fronds of vegetation on river banks. The most often seen damselfly is the common blue damselfly but it is only the males of the species that have this colouring: the females can be green, blue, black and white or straw-coloured apparently, while newly emerged males have black and beige markings. To see the two clutched in their rather brutal mating clasp is not unusual: they even fly through the air in this posture. There is also a blue-tailed damselfly with black body with a blue tip, and a green emerald damselfly. Banded demoiselle females are green too, becoming more bronze with age, while the males are metallic blue.

By rivers - particularly chalk streams - towards dusk, look out for swarms of mayflies, which dance up and down in the air. You can see them even in early May and indeed later in the summer, but late May or early June is supposedly the peak time. A clue to identification are the three long tail filaments visible as they float downwards in their dance and the striped black and white tips to their abdomens. One of the most ancient insect forms on the planet, they actually moult twice as an adult, the only insect type to do this - once into a dull brown sub-adult that emerges from the water and flies to a nearby bush (often getting eaten by trout or birds in the process), then a second time into a full adult. The latter has a digestive system which doesn't function, so they cannot eat: they therefore live only for a night or two, just long enough to mate.

This is also the month that you see cuckoo spit - the saliva-like liquid on plants that is actually produced by the froghopper.

More May pages:

© Peter Conway 2006-2018 • All Rights Reserved

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