3 Sawfly larvae on Alder

[poschiavanus]

This is for all you sawfly larvae geeks out there!

I managed to find three different sawfly larvae on a range of Alders today. The three are very distinct in appearance representing quite different modes of feeding.

1. Platycampus luridiventris (Tenthredinidae) on Grey Alder Alnus incana. This is an extremely distinctive larva, and, I think, not that frequently seen. I'd noted one yesterday when I was without a camera. Today I managed to find three in different locations, all on Grey Alder. I did search some Italian and Common (Black) Alder for larvae too, but didn't find any. The larva is very flattened and the pronotum sort of acts as a hood over the head. It could easily be mistaken for something else: a hoverfly larva for instance.



2. Alder Sawfly Eriocampa ovata (Tenthredinidae) on Italian Alder Alnus cordata. I was looking for more leaf mines when I noted little specks of frass and signs of feeding on a few leaves. I;d found a couple of larvae on the same plant about a month ago, so was not surprised to find a (rather small) larva when I turned over the leaf immediately above the frass.



3. Heterarthus vagans (Tenthredinidae) on Italian Alder. This is a leaf miner which creates large papery brown blotches on the upper surface of leaves. It's pretty common on ordinary Alder, but I was looking out for it to confirm my records of it from last year on Italian Alder. It's not enough to find the leaf mine because there is another a sawfly Fenusa dohrni which creates similar mines, and Fenusa is usually commoner. Fortunately the larvae are different, with Heterarthus have a distinctive shaped sternal plate on the pro-thorax and prominent black spots on the following segments. See Leaf Miners and Bladmineerders for more details.



Posch

[UB4 gardener]

i would have had the first one down as a hoverfly larvae. thanks for posting.

Chris