Nettle and meadowsweet galls

These strange swellings on leaves and leaf petioles of stinging nettle are the work of a gall midge called Dasyneura urticae, whose larvae develop inside the pouches. The midge lays its eggs on the leaf upper surface and when the larvae hatch they irritate the plant tissue on either side of the the groove in the leaf ribs, which grows over them forming a protective pouch lined with nutritive tissue. When the larvae are fully developed they escape through a slit in the gall wall and fall to the ground, pupating in the soil. 

You can find some excellent photos of the midge and its larvae at this web site

These are gall midge galls of another species of the same genus, Dasyneura ulmaria, on the leaf of meadowsweet Filipendula ulmaria. The galls and life cycle of the insect are broadly similar but in this case the midge lays its eggs on the underside of the leaf and there is only one generation each year.

All photos taken at Romaldkirk in Teesdale on 25th. September.

More photos of plant galls here.

Wildlife Viewed Through Beer Goggles: Stinging Nettles

My exploration of wildlife-themed beers has stalled a bit recently but here's an interesting example, brewed with additional stinging nettle flavouring, which adds a frisson of excitement to a quiet pint. Here's what the brewer, based at Matfen in Northumberland, says about it:

Nettle Ale 4.5% ABV

This ale can only be produced in the Spring, when the nettles on the farm are at the perfect stage to be picked. Based on a 14th century recipe, this ale is supposed to help the common cold and gout!

I haven't had a cold since I drank this and I haven't got gout (yet), so it clearly does exactly what it says on the bottle.

Stinging nettles are famous for the wealth of wildlife that they support, including numerous insects, of which thetiny  nettle tap moth Anthophila fabriciana (above) is one, currently breeding on the nettles in my garden. 


More wildlife-themed beers here.

Stinger

A stinging nettle Urtica dioica, spot-lit in a sun-fleck in the woods beside the River Swale, near Reeth this morning

Cycles of Abundance

As spring drifts into summer new insects appear on the scene, briefly flourish and then give way to another species. Recently we've had a virtual plague of St. Mark's flies, whose mating flights are beautifully described by Mark Cocker in today's Guardian Country Diary. This week, in my area at least, it's time for a mass emergence of this...

.....little metallic green weevil that seems to be on every stinging nettle leaf. It's Phyllobius pomaceus (identified with the help of B.N. Davis's excellent Insects of Nettles (Richmond Publishing Co. 1991)). This little weevil breeds on nettles, feeding on the leaves and at the moment every nettle bed has scores of them mating amongst the forest of stinging hairs on the host plant's leaves. They have a short season as adults and will have vanished again by early June, when their larvae feed underground.

This one has strayed onto a hawthorn leaf, overhanging the nettle bed.