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September insects, butterflies and animals

Other September pages: Berries, fruits, nuts and seeds • Leaf fall • Flowers • Birds • Weather

For pictures, more information and sound clips of the birds mentioned here, see the RSPB website. Put your cursor over any photo on this page to see its caption, or click here to see more September butterfly and insect photos.

There is still quite a variety of insects to see in September, but sightings are now fairly infrequent. An exception is when ivy comes into flower (usually in the second half of the month, though in places earlier), which can attract quite large numbers of insects to its late supply of nectar.

Especially fond of ivy are honeybees, wasps and flies of various kinds, whose humming as they surround the flowers reminds you of summer. The same insects may also congregate around michaelmas daisies. Otherwise, though they can be reasonably abundant at the start of the month, especially if the weather is fine, by mid month they are becoming quite scarce.

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. 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.

The wasps you see are redundant workers, who feed on rotting fruit before dying off: the jam in our cream teas provides an alternative. Again, only queens survive the winter, though one can sometimes see the occasional worker quite late in autumn. Hoverflies are also still sometimes seen, though most have disappeared back in August. The same is true of many different types of tiny flying insects too small for non-experts to identify.

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. The invasive harlequin ladybird unfortunately breeds much more frequently, laying eggs throughout the summer, which is why it is gaining the upper hand.

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 beetle in September, but numbers seem to be well down. The same is true of crane flies, grasshoppers and crickets in grassland. Particularly in the first half you can still see ants busily searching for food across grassland and bare ground: later in the autumn they seal up their nests for winter, but for now they are still quite active. Snails and other garden fauna also get much scarcer as the month goes on, but can still pop up when you least expect them.

Female garden orb spiders if anything become a bit more prominent this month, making big webs across corners in our gardens: do they do this because they are becoming more desperate for prey? 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. After she has mated, the female creates a silken cocoon in which she lays her eggs, which she will protect until she dies of cold later in the autumn. The spiderlings hatch in spring.

This is also the time of year when house spiders start to migrate into our houses - the ones you see are usually males on the hunt for females. The much more rarely seen daddy longlegs are their predators. 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 to be carried by the wind.

One other class of insect that is surprisingly active in September is dragonflies. Species still on the wing include the common darter and the beautiful green-blue southern hawker. Both can be seen till late in the month around ponds and streams - and sometimes further afield. Also on still water you may just 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 can be seen 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 appears in late August and early September if the summer has been good: these are the offspring of ones that appeared in July. This generation has 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), so they are 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.

A few peacocks may also be seen on the wing, though in theory they should be hibernating by now. Even hardier are red admirals. A migrant that should by rights be on its way south by now, they nevertheless pop up in all sorts of places right up to the end of the month: in 2017, indeed, they were the most common September butterfly. Some also 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 or peacock, but 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 see early in the month include painted ladies and clouded yellows - indeed, I have seen the latter as late as 28 September. 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.

On grassland you may still see meadow browns and common blues, very early in the month, and if you are lucky enough to find a colony of them (on south facing downland slopes, for example on the lower slopes of Ranmore Common near Dorking), the first half of September is actually a good time for adonis blues, who produce a second generation in September. 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.

Day-flying moths are largely gone, but you may see one or two, particularly at the start of the month. Then you can still see tiny white grass veneer (or perhaps the brown rush veneer which hides among dead bracken), and maybe a silver Y. I also once saw a speckled yellow and snout mid month and a common plume moth in the fourth week.

Lambs, bullocks and the deer rut

The number of pasture animals in the fields seems to reduce as the month goes on, but it is hard to put your finger on when. By this time many of those cute lambs that you admired in the spring have gone to the abattoir, but since they now look like adult sheep, their departure is not noticed. Sheep that will go onto be breeding ewes next year remain in fields.

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, whether dairy or beef cattle, I do not know. 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, though it climaxes in mid October. A wonderful place to observe this 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. 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, but fallow and sika deer also rut at around the same time as red deer. (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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