Sur Ulmus minor
on Prunus cf. cerasus. matches morphology of adult aptera, and primary host https://influentialpoints.com/Gallery/Myzus_cerasi_Black_cherry_aphid.htm
Caught in pitfall trap and collected for CAS with permit as part of a bioblitz, 1.0-1.5 mm.
On Tulip tree.
Aphids being tended to by American winter ants (Prelonepis imparis). On Norway Maple
https://influentialpoints.com/Gallery/Periphyllus_lyropictus.htm
Feeding on twigs of balsam poplar in a park. Last image shows host (see also https://www.inaturalist.org/observations/215163294 which is the same tree). For the galls see: https://www.inaturalist.org/observations/215389487. I was taking pictures of the galls the day before and I only noticed that there were aphids when I looked at the pictures at home. I returned to the tree one day later to get better pictures of the aphids.
on Carduus acanthoides
Aesculus
Really peculiar congregation of insects from a while back