Wednesday, 14 October 2015

Sunflower (part two)

The Sunflower continues to attract butterflies. This Red Admiral is the third species I have seen nectaring after the Small Tortoiseshell and Peacock last week. A passing Speckled Wood didn't seem so interested. I have seen  this butterfly on the flower for three consecutive days, now.

Red Admiral on the Sunflower
Red Admirals have two generations each year. The first generation is migrant from France (or perhaps even further south) in springtime, and their offspring feed on nettles, emerging from late August to October and then heading south. In recent years, however, adults have been found overwintering in the south of Ireland (and England), So, as warming takes hold, we're seeing a transition from solely migrant to partially resident populations.

Phenology has also changed in some moths. Some species were described by their flying (or emerging) dates. So we have August Thorn, September Thorn, Winter Moth, November Moth, December Moth, etc. But in the couple of hundred years since they were named, weather patterns have changed, and their names are not so accurate nowadays. This August Thorn is a new species for my list, and can be separated from the September Thorn by the kink in the rear band of the forewing (arrowed).

August Thorn moth
This is a locally common moth, feeding on larger broad-leaved trees.

I suppose it's worth pointing out that the season for September Moth often starts earlier than the August Moth! Of course, it isn't just moths that are altering emergence and migration patterns. Birds like the Redstart and Fieldfare that used to arrive as winter visitors have become very scarce nowadays, since they stay in situ and overwinter further north. Flowering plants are also extending their flowering season. Have a look in plant books from a few decades ago, and their 'flowering seasons' will surprise you.


The Weaver of Grass said...

Hi Stuart. It is a long time since I contacted you = not since I got my new computer and started again. However, I have been meaning to put you on my side bar for ages and shall right that now!
In the meantime, could you please look at my blog for today and see if you can identify the spongy looking mass of fungus, which seems to be puzzling everyone. You are always my first port of call. Hope all is well with you. said...

Stuart, Red Admiral is a very rare butterfly at our place. They say it has disappeared after opening a new factory of chemicals. I can't say for sure though. Maybe you can help with the explanation of their extinction.

stuart dunlop said...

The Red Admiral is a migratory butterfly. It arrives here in spring from France or further south, the females lay their eggs on nettles and then die. The caterpillars hatch and feed on the nettles through the summer, before pupating and emerging as new adults in autumn. So the adults are mostly seen in spring and autumn, with the occasional straggler in summer. I never see them in large numbers, and in some years I see none. You didn't say where you are, but I'd say the local availability of nettles would be a major impact on the numbers you see. If the chemical plant is causing a problem, it won't only be Red Admirals that are affected.

Coal said...

Thank you, Stuart, for the information! I'm from Sweden. Thermo Seed production has recently been started in Eslöv. I'm afraid it could be the reason for the butterflies disappearing.