Thursday, August 31, 2023

Alder moth caterpillar: a blast from the past

 It is almost exactly 50 years since I last found one of these: an alder moth caterpillar. Then, I was living in Warwickshire and it was curled up on a leaf, just as this latest one was, in a hedgerow in County Durham.

I have migrated north but so has Acronicta alni, except that it has extended its range more slowly. A  thorough guide to moths in County Durham published in 1986 doesn't list it, but now the alder moth is here, another insect species extending its range northwards, most likely in response to climate change. 

Thursday, August 24, 2023

Goat'sbeard pollination

 Flowers of goat'sbeard Tragopogon pratensis always close at around mid-day, giving the plant its alternative name of Jack-go-to-bed-at-noon. Most of the morning visitors seem to be hoverflies, like this marmalade hoverfly. Each inflorescence is made up from numerous individual florets that have a distinctive fail-safe pollination mechanism.

When each flower first opens the stigma and style extend upwards through a ring of stamens, collecting pollen on their outer surface and presenting it to visiting insects. At this point each floret is functionally male, but when the style is fully extended the sigma separates into two lobes that curl outwards, exposing their receptive surface to visiting cross pollinators arriving with pollen from another flower.

Then the stigma lobes continue to curl backwards, sometimes until they touch whatever pollen remains on the style surface, so self-pollinating if cross-pollination has failed.

Either way, the end result is a head of white whiskery seeds, that give the plant its goat'sbeard name, as large as a tennis ball and each seed equipped with a parachute to carry it away on the breeze.

Thursday, August 17, 2023

Inula hookeri and its pollinators

 This shaggy member of the daisy family, with its beautifully geometric spiral pattern of unopened central florets, originates from the Himalayas. In my garden it's a great attraction to bees, that appreciate the long period of pollen production that results from the sequential opening of all those florets.

Drone flies, like the one below, are also attracted to this flower, visiting to feed on the nectar.  

The most intriguing visitor for pollen collection is the leaf cutter bee. This uses a brush of long orange hairs on the underside of its abdomen to collect pollen, and in the final picture you can see how it walks around the circle of open florets, sweeping up pollen with those hairs as it goes. 

Wednesday, August 9, 2023

Blue tits and long-tailed tits feeding on aphids

 Blue tits and long-tailed tits often seem hyperactive, constantly searching for food. A moth larva would be a good meal, but they also eat much smaller prey, picking off aphids that infest plants. The blue tit below was eating aphids from the stalks of a hogweed umbel. The long-tailed tits, pictured futher down this post, were feeding on the woolly aphids that cover the trunk and stem of a crab apple tree in our garden.

Individually, tiny morsels of food, but since the aphids feed on plant sap, rich in sugars, they must provide a significant energy reward.

Tuesday, August 1, 2023

Angelica and hemp agrimony - seething with insect life in late summer

 Angelica sylvestris, a member of the Apiaceae (carrot family) is surely one of the best umbellifers for supplying insects with pollen and nectar. It thrives in moist soils places, often in dappled sunlight along woodland edges. The pictures below are of a greenbottle, a Darwin wasp (ichneumon) and social paper wasps feeding on nectar from its numerous tiny florets. The nectar is secreted in small amounts on each individual flower, so is easily accessible to short-tongued insects, without them needing to expend much energy; all they need do is wander across the umbel, incidentally pollinating the flowers as they feed.

Hemp agrimony Eupatorium cannabinum, a tall, pink-flowered member of the daisy family (Asteraceae) seems to be flowering spectacularly well along the Durham coast near Nose's Point this summer, in the company of meadowsweet and creeping thistle. Soldier beetles (last photo) are amongst the vast number of insects that visit its flowers, in the company of bees, butterflies and many species of fly.