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September insects, butterflies and animals

Other September pages: Berries, fruits, nuts and seedsLeaf fallFlowers and fungiBirdsWeather

Picture: a clouded yellow butterfly on common fleabane. Click here to see more September butterfly and insect photos. For more information on butterflies and moths see the Butterfly Conservation website.

There are still quite a variety of insects to see in September, but sightings are now fairly infrequent. An exception is around flowering ivy, as it attracts quite large numbers of insects to its late supply of nectar. The same can be true of other late flowering shrubs such as Russian vine and snowberry. Especially fond of these late blooming shrubs are honeybees, wasps and flies of various kinds. The same insects may also congregate around michaelmas daisies.

Honeybees spend the winter in hives, feeding on stored honey, but for bumble bees it is only the new queens who survive the winter, to found a colony next year. These are ones you see in September, the workers and this year's queen having died off by this point. The new queens are feeding up for their winter hibernation and looking for a hole in the ground to spend it in. Common carder bees, a bumble bee with quite a lot of ginger hairs, are particularly noticeable in September, being one of the latest flying bumble bees.

Some solitary bees may also still be around: there are some 300 species in the UK and some overwinter as adults and some as larvae. One that synchronises its lifecycle with the flowering of ivy is the ivy bee, which looks a lot like a honeybee to the non-expert eye. Large numbers of these can sometimes be seen on ivy bushes.

The wasps you see are redundant workers, who feed on rotting fruit before dying off: the jam in our cream teas provides an alternative, as do ivy flowers, which are actually one of the most reliable places to see them. These workers are on the wing all month, though only queens survive the winter. Hoverflies are also still sometimes seen, though most have disappeared back in August. The same is largely true of the many different types of tiny flying insects too small for non-experts to identify, though gnats keep going all winter, appearing in small swarms on still, sunny days.

Surprisingly, some insects are only just emerging in September. Seven-spot ladybirds - the classic red ones with black spots that everyone recognises - are just metamorphosing into adults in late August and early September, having grown from eggs laid in May. They will feed for a while and then find a cosy place (often in groups) to spend the winter in plant debris or leaf litter, before mating and laying eggs in the spring.

New green shield bug adults also emerge in September, though they are well camouflaged against plants and so hard to spot. Easier to see are brown dock bugs, whose adults appear in August and are still around in September. Both of these species lie dormant over the winter and lay eggs in May, just like ladybirds.

You can also see the occasional crane fly in grassy fields (loads in 2020 for some reason) and, particularly the first half of the month, grasshoppers and crickets. Also in the first half you can still see ants busily searching for food across grassland and bare ground: once the weather turns colder, they seal up their nests for winter. Snails and other garden fauna get much scarcer as the month goes on, but can still pop up when you least expect them.

Spiders actually become more prominent this month, as orb weaver spiders make their classic webs of concentric circles in our gardens. The ones you see are females (the males are much smaller), who have mated and made a silken cocoon in which to lay their eggs. They will guard these until they die of cold later in the autumn and the eggs will then go on to hatch in the spring. The web doesn't stay sticky for long so the spider will rebuild it every day or two, consuming the old web as she goes - a task that takes as little as half an hour.

This is also the time of year when you notice alarmingly large house spiders in your house. Contrary to popular myth they do NOT come inside this time of year to escape the cold: they are in fact there all along but remain hidden, manning webs in obscure corners. But at this time of year males come out of hiding to search for a mate, which is why you encounter them on the stairs or walking across your living room. Please leave them alone: they will not harm you. They have their own predators - cellar spiders - that we never see.

The morning dew also reveal the threads that money spiders use to "balloon" out across fields: they attach their threads to a blade of grass and then launch into the sky using air currents. They do this in order to avoid mating with siblings. One field can have millions of threads.

One other class of insect that is surprisingly active in September is dragonflies. Species still on the wing include the common darter, the beautiful green-blue southern hawker, and the chocolate-coloured migrant hawker. All these can be seen till late in the month around ponds and streams - as well as further afield. Just occasionally very early in the month you may see a common blue damselfly. On still water you may still see pondskaters.

Butterflies and day-flying months

Butterflies become much scarcer in September, but you can still see some when the sun shines and there are flowers for them to feed on. White butterflies are on the wing until late in the month. When they stop long enough to be identified (which is rarely) they often seem to be small whites, though large or green-veined whites are possible too. Speckled woods also reliably last till later in the month.

A new generation of commas and small tortoiseshells may appear in late August and early September if the summer has been good, though this rarely seems to happen these days (and small tortoiseshells are becoming distressingly rare). These are the offspring of the generation that appeared in July and have only one aim, which is to find a place to hibernate (technically, diapause: the butterflies switch off their metabolism altogether but can switch it on again immediately if disturbed). They are therefore not on the wing for long. Commas are particularly hard to see because with their wings closed they look like a dead leaf - the perfect camouflage for this time of year. If the summer was a poor one, this generation is skipped altogether and the July one goes straight into diapause. In both cases the butterflies then emerge in March to mate. The occasional peacock or brimstone is also possible, particularly early in the month.

Another butterfly that might just pop up at any time of the month is the red admiral: in 2017, indeed, they were the most common September butterfly. Though a migrant which should be on its way south by now, some even manage to survive the winter, emerging on warm days in January, February or March. There is as yet no evidence that they then go on to mate in spring, but they seem to be on their way to becoming another diapausing butterfly.

All of these overwintering butterflies - comma, small tortoiseshell, peacock and particularly red admirals - may turn up on flowering ivy late in September or even into October, long after you have concluded that you have seen your last butterfly of the year.

Other migrants you might in the first three weeks of the month include painted ladies and clouded yellows. It used to be thought that painted ladies simply died off at the end of the summer, but science has now established that they migrate back south again to their winter breeding grounds in Morocco, using high altitude winds. In the case of clouded yellows, any you see now are quite likely to be the offspring of eggs laid earlier in the summer: you may therefore see several in one place.

On grassland you may still see meadow browns very early in the month, while common blues can turn up in the same habitat as late as the third week. The first half of the month is also a good time for adonis blues, if you are lucky enough to find a colony of them. They live on south facing downland slopes, for example on the lower slopes of Ranmore Common near Dorking or in Mill Hill Reserve near Shoreham-by-Sea, and produce a second generation from mid August onwards. In 2018 and 2020 a few holly blues also survived into the first week, and in 2020 long-tailed blues (a continental species) were sighted on the south coast near Kingsdown and Seaford.

Tiny small heath butterflies can in theory be seen all month, but are most likely right at the start. You may just see a small copper in the first half of the month and in theory they can produce a further generation towards its end, though I have never seen this. Early in the month you may see some surviving brown hairstreaks on and around blackthorn bushes, but this is a very elusive butterfly that you are only likely to spot in a site where it is known to be present. Also elusive are wall butterflies, which can still survive on the south coast in warmer Septembers: in flight they look a bit like a meadow brown in a hurry.

Day-flying moths are largely gone, but you may see one or two, particularly at the start of the month. These include the tiny white grass veneer (or perhaps the brown rush veneer which hides among dead bracken), and maybe a silver Y. I have also twice seen snouts mid month, and once each a speckled yellow, a hummingbird hawkmoth and a large yellow underwing: also a tiny straw-barred pearl, and a common plume in the fourth week.

Lambs, bullocks and the deer rut

The number of pasture animals in the fields reduces as the month goes on, but it is hard to put your finger on when. Those cute lambs of early spring now look like adult sheep, but early in the month it is still possible them from their mothers because the mothers have been shorn and the lambs have not. Later it is hard to tell, probably because the lambs have now gone to the abattoir. The breeding ewes will remain in the fields all winter.

You can still see herds of bullocks - presumably not long for this world - but strangely there also seems to be an upsurge in cows with calves this month, presumably beef cattle, since dairy calves are separated from their mothers at birth. One has a sense that dairy herds are reducing in number, though they should in theory not go into barns until later in October. How fast the grass is growing and how soft the ground is may be decisive factors.

Late September sees the beginnings of the deer rut, which climaxes in October. (The reason for this timing, incidentally, is so that the young can be born in spring, when the weather is warming and the grass is starting to grow again.) A wonderful place to observe the rut is Richmond Park in London, where dominant red deer males gather harems of females (or rather the females gather round the male – it is they who choose where to be) and mate with them, while defending them against challengers. In late September all this tends to be at a fairly early stage, with the males roaring at each other (they build up their throat muscles over the summer so they can extend their larynx to produce deeper tones) and rubbing their antlers in the bracken to mark out territories. Some harems may also be starting to form. For more information on the red deer rut at its height, see the October deer rut page. For photos click here.

Red deer are not a wild species in southern England (though they can also be found on the Knepp Wildlands near Horsham), but fallow and sika deer also rut at around the same time. (Roe deer, the other common wild species, ruts in late July and early August). If you are lucky enough to spot signs of these in the woods, keep your distance, however. The deer in Richmond Park also need to be treated with respect, but are obviously more used to being watched by humans.

More September pages:

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