Subject: Orange Abdomen – Plant eggs in stems?
Location: Mira, Venice, Italy
May 17, 2015 12:26 am
Hi dear Bugman,
On these roses these insects, I counted 4, proceeds undisturbed to crack the stems, leaving behind a kind of scar. I could go as fat as touching them. The have this very bright orange abdomen and very dark rest of the body and wings. The length is about 1-1.2cm. Apparently the upload does not work. I posted two pics:
I’m really curios about this. Glad to find a service like this online. Hope it works
Signature: Lord of the manor
Dear Mauro, Lord of the Manor,
These are Sawflies, nonstinging relatives of Bees and Wasps whose larvae feed on plants, sometimes eating the leaves, and sometimes feeding on other portions of the host species. We quickly identified your Sawflies as Large Rose Sawflies, Arge pagana, on the Dutch site tuin-thijs.com where it states: “The Large Rose Sawfly saws a hole in a Rose (plant) and lays eggs. The larvae eat the rose. But usually there is not much damage, because the larva has many natural enemies.” On Nature Spot it states: ” Like all sawflies, female Large Rose Sawflies are in possession of a little saw. With it they make parallel cuts in the fresh shoots of the host plant. In the cut a bunch of eggs is deposited. The larvae hatch quite quickly and move in a group to the freshly emerged leaves. The young larvae (yellow with black spots) stay together for quite some time, capable of eating the entire shoot. Older larvae lead a more single life and eat from older leaves as well.” We also located an Italian site, Agraria.org that might have helpful information for you.
Thanks Daniel for the quick and comprehensive answer! I took pictures of the larvae last year without knowing they were Sawflies.
Thanks also for the great service you are providing!