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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, small tortoiseshells may just crop up but are generally not evident after late April. However peacocks can still be seen fairly regularly in the first half of May, with the occasional one, looking rather worn out by now, on the wing 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. 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.

The striking yellow brimstone is more abundant and lasts longer, a common sight 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 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 (see below): the key to identification is the lack of black wingtips, and the shape of its wing and its green underside if you see it at rest, which it always does with its wings closed.

The lovely orange tip is mostly seen in the early part of the month, but some years it flies all May, particularly if cold weather in April has delayed its emergence, and in others you get the occasional straggler late in the month. 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 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 very unmistakable green stripes on the underside of their hindwing, while their upperwings have faint grey lines across them. They also have grey wing tips, but descending down edge in a series of blobs. They seem to make up a large proportion of the whites one manages to identify in May, but this is probably because they are slightly more inclined to settle. 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, 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 look a bit like a silver flash 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 low-flying butterfly is likely to be a common blue, some of which appear from quite early in May, though they are more common 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 or Mill Hill Reserve north of Shoreham-by-Sea - but 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, but its female is very rarely seen). However, if you see a very small butterfly with these markings, particularly but not exclusively in the second half of the month, the 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 is that the orange chevrons around the wing edge are uniformly bright on the brown argus, 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 (and yes, despite its name it is brown not blue). It likes very bare ground - often little more than naked chalk dotted with flowers - with patches of kidney vetch, its caterpillar food plant, nearby. It is on the wing in the second half of the month and you really have to go to a site where it is known to be in order to see it. When you do, its beige grey underwings are the key to identification. One well-established colony is on the slopes of Pewley Down near Guildford and others can be found on Hutchinson's Bank and Chapel Bank near Addiscombe. I have also seen them on the downs above Otford in Kent and on 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. Towards the very end of May in longer grass 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.

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 when at rest due to its green underwing, which means it blends in with the downland shrubs it usually perches on. Try Aldbury Nowers or the lower slopes of Pitstone Hill near Tring, the North Downs above Shere, 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, in the south east they are now only found on coasts (for example on 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 - 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). 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.

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 Tugley and Oaken Woods to the south east of Chiddingfold near Haslemere, 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 Addiscombe on the southern edge of London, 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, one of which is Abbot's Wood near Polegate and another Rewell Wood near Barnham. The very elusive duke of burgundy might just be seen in May on Steps Hill 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.

Day-flying moths

It is easy to mix all these 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 and both easily confused with the dingy skipper butterfly, as noted above). The fairly common speckled yellow, found in various types of habitat including hedgerows and downland, also looks like a small butterfly.

Perhaps the main difference between moths and butterflies, however, is that 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.) Less easy to confuse with butterflies are the bright red and black five-spot burnet and, occasionally, the equally colourful cinnabar moth.

Other moths you may encounter include the lace border, found on chalk grassland in the North Downs, the yellow shell, and the yellow belle, which is mainly coastal. On heathland or in rough grassland you may see a common or latticed heath. 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 habitats but are often seen on downland. 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, the straw dot, and the small purple-barred, all of which occur on downland. In the same habitat, as well as other grassy places, you also see grass veneer moths, which look like tiny white butterflies as they flit around grassland but then close their wings when they come to rest and almost completely disappear. Equally tiny, but looking more like a silver-winged fly than a moth, is the green longhorn, which forms mini-swarms, taking off and landing on the leaves of shrubs next to downland and other open 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 in the first half of the month in large swarms 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 eggs, with nectar for food, and 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). They 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 - 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.

Other insects have evolved to look like bees for protection from predators - this is true of several 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, a 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. Less charmingly, they are also cuckoos; that is, they parasitise on the young of solitary bees and wasps. They carry the bee imitation as far as making a very bee-like buzzing noise.

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, as well as tiny insects that congregate on buttercups or dandelions, fly into your mouth 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. The invasive harlequin can also be seen in a variety of different liveries: it breeds all summer, out-competing native species (though it did not seem to do so well in 2020 and 2021).

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, hawthorn shield bugs and dock bugs have emerged from hibernation and are now mating, 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 black bloody-nosed beetle, bright red cardinal beetles, black-backed soldier beetles, iridescent green or gold leaf and swollen-thighed beetles on buttercups or hawkbits, and rose chafers that feed on dog roses and similar blooms. Other insects to be seen include pondskaters on still water, while crane flies can be abundant in grassy fields.

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. Less common is the beautiful demoiselle with its striking brown wings (again the male having a blue body, the female metallic green). The males of both of these species jockey for position on fronds of vegetation on river banks.

Away from water the most often seen damselfly 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 apparently, 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, and the large red damselfly.

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.

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, they actually moult twice as an adult, the only insect to do this. They first emerge 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 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.

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).

More May pages:

© Peter Conway 2006-2021 • All Rights Reserved

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