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May butterflies and insects

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Picture: a green hairstreak butterfly on horseshoe vetch. Click here for more May butterfly and insect photos. For more information on butterflies and moths see the Butterfly Conservation website.

May sees the butterflies 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, the most obvious and abundant is the striking yellow brimstone, which can be seen throughout the month, with some still around into June. It is a "mobile" butterfly - that is, its males range widely across the countryside rather than defending a territory. For this reason they usually fly past you in a hurry.

The female brimstone is a very pale yellow and can be mistaken for one of the white species (see below), though it is usually larger. It is often seen fluttering low over shrubs (buckthorn being the caterpillar food plant) looking for places to lay eggs. The shape of its wing and its green underside is a reliable way to identify it if you see it at rest, when it always has its wings closed.

Otherwise, peacocks can still be seen fairly regularly in the first half of May, with the occasional (usually rather worn out) one on the wing right till the end of the month. They look almost black in flight due to their dark underwings, but have a handy habit of landing for a rest on paths, making their colourful upperwings easy to see.

Commas are much more occasional in May, but you may just see a survivor even late in the month. Small tortoiseshells are generally over by the end of April, but may just be seen in the first week. In 2024 they seemed to be almost entirely extinct in the south east, however.

The lovely orange tip is mostly seen in the first half of the month, with the occasional straggler possible thereafter, but some years it is abundant all May, usually because cold weather in April has delayed its emergence. 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. It smaller and has a slightly more fluttery flight than the whites, but the real 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 the other commonly seen white butterflies, which are 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, having overwintered as pupae, with some small and large whites also migrating from the continent. But it is impossible to tell them apart as they flutter past.

Green-veins seem to make up a larger proportion of those one does see at rest, probably because they are slightly more inclined to settle. As their name suggests, they have green stripes on the underside of their hindwing, as well as faint grey lines across their upper wings. Their grey wing tips descend a bit down the wing edge in a series of blobs, while on the small white the grey tip is much neater. Large whites (which are not necessarily that big) have black wing tips extending down both edges of the wing.

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, often concentrated near the south coast. The red admirals are migrant females who have already mated on the continent and lay eggs here immediately on arrival, though it is just possible that you may be seeing one that has successfully overwintered (see April butterflies and insects).

Painted ladies mate once they arrive in the UK and may be seen right from the start of the month. The males often rest on an earth path and then fly around very fast and low to the ground when you disturb them (stand still and they often settle again). In both species their offspring go on to make up a (hopefully) much more numerous summer generation, boosted by further migrants. These then travel back southwards in the autumn.

Look out also for tiny blue butterflies during May. Near brambles, ivy bushes or hedgerows these are almost certainly holly blues, which have a pale blue underside and may look a bit silver as they fly past. They are also the only blue to fly at shoulder height, while the other blue species stick close to the ground.

On grassland that ground-hugging butterfly is likely to be a common blue, some of which appear from quite early in May, though they are more numerous in the second half of the month. They can be distinguished from a holly blue by their brown underside with black spots.

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, however. These butterflies live in small, discreet colonies - for example the southern slopes of Ranmore Common near Dorking and Mill Hill Reserve or Anchor Bottom north of Shoreham-by-Sea - and can be very numerous within them.

Telling them apart from the common blue is a challenge. The adonis is a lighter blue, but the common blue looks fairly light too in certain lights; 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.

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). However, if you see a very small butterfly with these markings, particularly but not exclusively in the second half of the month, a brown argus is also possible. Its male is smaller than the female common blue but its female looks pretty identical to its sister species.

One clue to identification of the brown argus is that the orange chevrons around its wing edge are uniformly bright, while on the common blue female they fade away towards the top edge. There are also tiny differences between the two species in the black spots on the underwing. 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. It is its upperwings that are brown: its beige-grey underwings can look blue in certain lights. It favours relatively short grass, with its caterpillar food plant being kidney vetch. It is not impossible you might see one in the first half of May, but it is really on the wing in the second half.

Though they are getting a bit more common in response to conservation efforts, you really need to go to a site where small blues are known to be present in order to see them. These include Pewley Down near Guildford, Hutchinson's Bank and Chapel Bank near Croydon, Fackenden Down near Otford, Yoesden Reserve in the Chilterns near Saunderton, Magadalen Down near Winchester, and Compton Down on the Isle of Wight.

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 (see below), so small and inconspicuous are they. Both are mainly found in downland or short, rough grassland (try the slopes of Pitstone Hill near Tring, the downland above Shere, the lower slopes of Ranmore Common near Dorking, or Hutchinson's or Chapel Bank) but they may crop up in other locations.

If you see a small orange butterfly it is likely to be a small heath. These live mostly on downland and are only ever found close to the ground. They land frequently and always close their wings when they do so. Look carefully, however, because what you are seeing might just be a small copper. Much more adventurous and more elusive, it tends to crop up when one least expects it - on grassland, but also on flowery hillsides, even woodland rides.

Towards the very end of May in you may also see the large skipper, a tiny orange butterfly with a whirring flight that looks exactly like a moth, particularly in the way it folds its wings on landing. It is also a grassland species, but often seems to be found perching on brambles or shrubs on the edge of grassy areas.

One other very tiny butterfly, looking brown in flight, is the green hairstreak. It is fiendishly hard to spot when at rest due to its green underwing, which means it blends in with the shrubs it usually perches on - often in downland areas, where hawthorn sometimes seems to be favoured, but also on heaths or other open spaces, where it may be found on gorse, broom or even bracken. Try Aldbury Nowers or the lower slopes of Pitstone Hill near Tring, Fackenden Down near Otford, Hutchinson's or Chapel Bank, the lower slopes of Ranmore Common, or Wye Nature Reserve.

Rarer butterflies in May 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, they are now only found on coasts in the south east . They like to sunbathe on paths (and also supposedly walls, hence their name) but are very flighty and easily disturbed. Even in sites where they are found, they are generally more common from mid July to August, when they have a second generation.

Places to look for walls include the cliffs near St Margaret's Bay and Kingsdown, the shingle area between Seaford and Newhaven, the South Downs north of Shoreham-by-Sea and Lancing, in the grazed area in Folkestone Warren, and - further afield - on the south west coast of the Isle of Wight, the ridge between Kimmeridge and Swyre Head near Swanage, and on Portland Bill.

May is also the month to see the wood white, a delicate butterfly that is much smaller and more feeble in flight than the common white species, and which is these days only found in a few strongholds in England. One is Oaken Wood and its environs to the south east of Chiddingfold near Haslemere, which holds nearly a quarter of the UK population, and where they are relatively easy to spot on sunny woodland rides.

Another highly localised butterfly is the glanville fritillary, which can be found on the crumbling cliffs of the south coast of the Isle of Wight in the second half of the month. In 2011 some of these were also introduced to Hutchinson's Bank near Croydon and have flourished there ever since, spreading to nearby Chapel Bank as well.

Equally site-specific is the beautiful pearl-bordered fritillary, once a common butterfly of coppiced woodland, but now only known in a few locations in the south east, which include Abbot's Wood near Polegate, Rewell Wood near Barnham, and Verdley Wood midway between Haslemere and Midhurst. They can also be found in the Pignal and New Copse Inclosures in the New Forest.

The elusive duke of burgundy might be seen in May at Incombe Hole near Ivinghoe Beacon, Hutchinson's or Chapel Bank, and on Kithurst Hill above Storrington on the South Downs, while towards the end of the month and in the west of our region (for example in the Wiltshire Hills beyond Salisbury or at Bentley Wood near Dean), you may come across a marsh fritillary. Some individuals have also been seen in recent years at Hutchinson's Bank, Incombe Hole and Yoesden Reserve near Saunderton in the Chilterns.

Day-flying moths

It is easy to mix small butterflies up with various day-flying moths that are also on the wing in May. Dingy or grizzled skippers, for example, look very similar to brown moths such as the burnet companion and the mother shipton, both grassland species. The fairly common speckled yellow, found mostly in open woodland but also sometimes on scrub or downland, also looks and behaves like a small butterfly.

Speckled yellows apart, perhaps the main difference between moths and butterflies from an observer's point, however, is that many moths immediately head for cover when disturbed. This is certainly true of the white common carpet, silver-ground carpet, and the treble bar, all of which can be also found along hedgerows, in grassland and in a range of other habitats. (There is also a green carpet, but I have only ever seen this twice.)

Exceptions to this rule, and less easy to confuse with butterflies, are the bright red and black five-spot burnet and the equally colourful cinnabar moth. Their bright colours indicate that they are poisonous to predators: consequently they are not at all shy and can be easily seen flitting about (on downland in the case of five-spot burnets, in places where ragwort grows in the case of the cinnabar).

Other moths you may encounter include the lace border, found on chalk grassland in the North Downs, the yellow shell (all sorts of habitats), and the yellow belle, which is mainly coastal. On heathland or in rough grassland you may see a common or latticed heath, while the brown silver-line is found among bracken.

Silver Y moths also turn up in May some years: a migrant with a very whirring flight, they can be found in all sorts of places but are often seen on downland. Just occasionally on woodland rides and scrubby downland you see a striking white female muslin moth (the male is only nocturnal), while at the end of the month you may be lucky enough to see the black chimney sweeper in meadows in which pignut grows.

Note also the very tiny micro moths, which include such species as the small yellow underwing, small purple and gold (aka mint moth), small purple-barred and wavy-barred sable, all of which occur on downland, while the straw dot prefers damp meadows and woodland.

Equally tiny, but looking more like a silver-winged fly than a moth, is the green longhorn, which has enormously long antennae and forms mini-swarms, taking off and landing on the leaves of shrubs next to downland and other open areas.

Much more common than these - they are all over the place if you get your eye in - are grass moths, which look like tiny white butterflies as they flit across grassland, but then close their wings when they come to rest, making them seem to abruptly disappear. There are 39 species of these in the British Isles and if you see them at rest (and have a magnifying glass handy...) they can be fascinating in their variety and the ingenuity of their camouflage.

You may come across webs containing caterpillars on the top of hedgerow shrubs such as blackthorn or spindle. These are created by moth species such as the lackey and ermine (particularly the spindle ermine) in order to protect their larvae from predation, and can cover large areas.


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 you may occasionally see swarming in the first half of the month is the St Mark's fly. Its legs trail below it when it is on the wing, 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. Alexanders are a favourite food plant, so it may be easier to see in coastal locations, but it is also found inland.

Otherwise, there are plenty of bees around - honeybees, solitary bees and also bumble bees. Solitary bees mate singly, like any other insect, and then the female lays individual eggs, with nectar for food, each in their own hole, and then seals them up until the larvae emerge as adults. Some are cuckoos - that is they lay their eggs in the nest holes of other solitary bees, so their young can feed on the other bee's larvae.

Honeybees live in colonies, and if you see one on a flower or blossom there will usually be lots of others nearby: often it is the gentle hum of their flight that alerts you to their presence (and tells you that this is a honeybee not a solitary bee: solitary bees do not hum).

Honeybees may swarm during May, which is how new hives get founded. Either a new queen or the existing one leaves the hive with most of the bees then flying, and while they are searching for a new place to set up you see hundreds of them coating a branch or a fence post, or in the cleft of a tree - a scary sight, though they are usually not aggressive unless you do something to alarm them. In the old hive, a new queen emerges to rule the new colony.

The bumble bees you see earlier in the month are still queens. 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 and building up a ball of pollen to feed their first young on. By the start of May their nests have been established and from around mid month the smaller (and much more numerous) workers start to emerge. From this point on the queen never leaves the nest again; she becomes a machine for producing larvae.

Just occasionally you can also see queen wasps still in May. There are also ichneumon wasps, of which there are all sorts of weird and wonderful species. These are solitary and also cuckoos, using the larvae of other species as food for their young.

Other insects have evolved to look like bees for protection from predators - this is true of many species of hoverfly, which can be seen everywhere at this time of year (they can easily be distinguished from bees by their charming capacity to hover absolutely immobile in mid air).

Notice also the bee fly, another hovering fly with a fat furry body which is found more in the early part of the month, feeding on flowers much like a hummingbird, using its long proboscis. Cute though they look, they are yet another insect that lays their eggs in the nest of other species, their young feeding on the larvae of solitary bees and wasps. They carry the bee imitation as far as making a very bee-like buzzing noise (which is actually produced by their wings).

House flies (aka bluebottles) are also about, and as the month goes on can become a nuisance, buzzing around your kitchen. May also sees a lot of other flies of various sizes (including big ugly flesh flies, the ones that produce flesh-eating maggots, and exotic-looking scorpion flies).

Note also the myriad tiny insects that congregate on buttercups or dandelions, fly into your mouth or eyes when you are running or cycling, swarm at dusk or just above the surface of rivers, or produce itchy bites on your arms and legs. One becomes aware of the amazing variety of insect life, most of which passes beneath our attention.

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.

In the 2010s the invasive harlequin ladybird could also be seen in a variety of different liveries: it breeds all summer and so it was feared it would out-compete native species. In recent years it seems to be much less common, however.

May is a good month to see shield bugs of various types, which have similar life cycles to those of seven-spot ladybirds. Thus the green shield bugs, hairy shield (aka sloe) bugs and dock bugs you see, often on shrubs of various kinds, have emerged from hibernation and are now mating and laying eggs that will hatch into a new generation at the end of the summer.

Mating is also uppermost in the mind of a multiplicity of beetles in May, to be seen particularly later in the month, including the classic black bloody-nosed beetle, bright red cardinal beetles, red or black-backed soldier beetles (the black-backed ones sometimes known as sailor beetles), iridescent green or gold leaf and swollen-thighed beetles on buttercups or hawkbits, and rose chafers that feed on dog roses wayfaring tree flowers and other flowering shrubs. There is even a four-spotted leaf beetle that looks like an oversize ladybird.

In the second half of May you also start to see dragonflies and damselflies, the latter including the beautiful banded demoiselle, the males metallic blue with hypnotically patterned double wings, the females green initially but becoming more bronze with age. The males jockey for position on the fronds of vegetation on river banks.

Similar, but with brown wings and found further away from water (eg on woodland rides), is the beautiful demoiselle, again the male having a blue body, the female metallic green.

The other damselfly that is frequently seen is the common blue damselfly, but it is only the mature males that have this colouring: the females can be green, blue, black and white or straw-coloured, while newly emerged males have black and beige markings. To see male and female clutched in their rather brutal mating clasp is not unusual: they even fly through the air in this posture.

You may also see in May the blue-tailed damselfly with a black body and a blue tip, the azure damselfly which differs in tiny details from the common blue, the white-legged damselfly, the males of which are striped white when immature but go on to be a light blue, and the large red damselfly, whose colour makes it gratifyingly easy to identify.

Dragonfly species include the broad-bodied chaser, the male having a broad blue abdomen and the female a brown one fringed with yellow, and the black-tailed skimmer, where the male has a thinner blue abdomen tipped in black, and the female is a striking yellow. Right at the end of the month in warmer Mays you may just see the magnificent green and blue emperor.

By rivers towards dusk - particularly chalk streams - look out for swarms of mayflies dancing 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 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 creatures on the planet, mayflies actually moult twice as an adult, the only insect to do this. They first emerge from the water during the day as dull brown sub-adults that struggle to work out how to use their new wings, taking off and then landing again (a process imitated by fly-fishing) and often getting eaten by trout or birds in the process.

If they reach the safety of a nearby bush, they then moult a second time into full adults, taking to the air later in the afternoon. In this form they have 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. It is the males that do the dance: the females fly through the swarm to find a partner, and then lay their eggs back in the water to start the lifecycle all over again. After this they die.

Other insects to be seen include pondskaters on still water, while crane flies can be abundant in lush grassy fields (where you may see them mating): watch for them darting away from your feet as you walk.

This is also the month that you see cuckoo spit - the saliva-like liquid on plants that is actually produced as a protective layer by the larvae of the froghopper (so called because the adult makes sudden big jumps: spittlebug is not surprisingly another name for this insect). It usually appears in the second half (occasionally in the second week), lasting into June.

More May pages:

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