Hungry little blighters
I mentioned sawflies the other day but I just noticed some more at the weekend. The larvae are munching their way through the leaves of one of my Betula albo-sinenensis – no common silver birch for them. I am fairly sure the species is Nematus septentrionalis. These have two or more generations a year and when the larvae are full they drop to the ground to pupate and hatch as adults. Like other sawflies they are gregarious and like to munch away in groups.
And when you get too close or you startle them they arch their backs, presumably to make the group look bigger and frighten off predators.
The Biking Gardener 
Gooseberry sawflies were a curse here years ago but I no longer grow gooseberries.
That is probably the easiest way to avoid the problem! My gooseberries have only been in a year and they got clobbered this year – I don’t know where they came from or found my plants – there can’t be any for miles around!
I recall a suggestion to deal with gooseberry sawfly from a gardening book published in the early 20th century. One was to spread lime under the gooseberry bushes and then discharge both barrels of the shotgun, firing just above the line of gooseberries. The sawflies will fall from the bushes onto the lime! Gone!
When we used to do the Roadshow we used to give this advice too, mainly copied from colleague Geoff Amos who was a great source of stories. He would say how they hate loud noises and that is why the shotgun and lime trick worked. When you fired the shotgun they would put their hands over their ears and so would let go of the branch and drop into the lime.
I want to see photographic proof of their putting their hands over their ears! LOL
Interesting!
Blue Rock Horses Frederick County, Virginia bluerockhorses.com
ICK! . . . but also silly. They think they are frightening?