Longhorn found in aquatic flower

[LarvaHunter]

I found a longhorn beetle, that I haven't seen before in a lake inside an aquatic plant flower.

The plant was Cow Lily (Nuphar advena). I've read these other beetle larvae live in them, but it did not say longhorns do. I wonder how many beetles live in these aquatic flowers now.

 

[Matt]

Are you sure it wasn't a Chrysomelid leaf beetle along the lines of a Donacia species, these can look very like Longhorn beetles at first glance.

Donacia aquatica.