Thursday, 4 April 2013

Season under way

When I woke up this morning and saw the clear blue sky stretched all the way to the horizon, I knew that today was the day for the season to start. I waited until mid-day before I ventured forth, since insects need time to emerge, inflate and dry their wings and have a few test flights before they start nectaring, not to mention a decent temperature to support flight.


The first specimen I saw was a female Eristalis tenax, which was entirely expected (see my earlier post here). She was on a Dandelion, which flowers for 12 months around here:


Female Eristalis tenax on Dandelion
I chose that shot because it shows the very wide dark facial stripe.

I went to a sunny bank where the Celandines are in full bloom and quickly found a male Platycheirus albimanus, also on Dandelion:  

Male Platycheirus albimanus on Dandelion

I noticed that this close-up shot shows one of the conclusive identification features: a clump of thick, dark bristles under the front leg, near the top:
Male Platycheirus albimanus, showing dark tuft of hairs
Although this isn't the earliest I have seen this species (last year I saw it on March 27th), it is a good indicator that we're catching up at last.

Fungal rusts are usually specific to one family of plants, although some are unique to species. This is Puccinia umbilici on Navelwort - Umbilicus rupestris:

The fungal rust Puccinia umbilici on Navelwort
Notice how fresh the Navelwort leaf is: rusts don't waste any time.

I suppose I should clarify my 'specific to one family of plants' statement. Fungal rusts very often have two hosts which are completely unrelated. This odd situation arises because fungi need somewhere to exist when the primary host loses its annual growth (perennial) or dies altogether (annual). So they tend to live on one host in the summer months before transferring to their overwintering host. The most extreme example I know of locally is Puccinia sessilis which spends the summer on members of the Allium family (in my case on Ramsons), but overwinters on Canary Reed-grass, which I don't have locally. The airborne spores must therefore travel many miles to ensure their overwintering survival. The detail is even more complex, since the fungi have different parts of their reproductive cycles on differing hosts. Sometimes I begin to wonder if these travelling rusts are actually an amalgam of two species. The more I study wildlife, the more complex it becomes.

Finally for today, a shot of the fungus Milesina scolopendrii on Hartstongue fern:

Milesina scolopendrii on Hart's-tongue Fern
This one doesn't need an alternate host, since the fern is evergreen, but as an example of perversity, complexity and downright confusion, other members of the Milesina family (which all infect different ferns) rely on Pine trees as an alternate host.

3 comments:

Gill said...

Another fascinating post. I wish we had such signs of spring; it is sunny but still bitterly cold.....

"but overwinters on Canary Reed-grass, which I don't have locally. The airborne spores must therefore travel many miles" or, it could overwinter on some other related grass that no-one's sussed yet?

Caroline Gill said...

Still bitterly cold here too in Suffolk ... snowing most of the day. I have yet to see my first butterfly, and yet two years ago, I saw one nectaring on heather in mid-February.

stuart dunlop said...

My first butterfly of the year was a Small Tortoiseshell today. I'd say we're about 2-3 weeks behind a 'usual' year, and perhaps 4-5 weeks behind last year, which was very early. It shows just how flexible our wildlife is in terms of emergence and flowering. It also shows that synchronisation between species is even more important than it might seem at first glance: there's no point in an insect emerging if there's no pollen, and there's no point in a flower opening if there are no pollinating insects. I also saw a queen Bombus terrestris hunting around for a nesting spot today.