Yes. Arge species have glands on the underside of their abdomen. The glands emit volatile aromatic hydrocarbons into the air. Ants eat a lot of sawfly larvae but in experiments, ants have been seen to scurry away from Arge larvae that behave in this way.
Horses for courses as they say. I buy gooseberry bushes just for the sawflies. 🙂
One or two species can be destructive but plants usually recover. Most of the 550 species in the UK don't cause a problem. All are important food for birds and like bees, many are pollinators too. Some are good at controlling other insect pests.
Chemical warfare in action.
Probably annulipes yes. Need final instar to be sure but looks to have the dark head band and dark hind thoracic legs.
It is a bit tenuous. Not sure I'd accept it as a record but could be.
Yes. Looks good to me.
A bit tenuous, but I would say so. The scars result from larvae that die before they have fully grown so could be that the larva didn't last long. Successful larvae leave the apple and the apple then falls off whilst still quite small as part of the June drop.
Probably more records that aren't on iRecord. Certainly commoner down south. Nice find anyway. 👍