An aphid associated with Birch.  Winged adults and nymphs are green, oviparae are brownish and males are reddish, but all forms have very long and thick antennae that are black except at the base.  Unusually for aphids, they are found on upper surface of the leaf, and are solitary or present in very low numbers.

Good quality photographs; you must note the host plant

Birch trees

Rare

Rarely recorded; the Croft record is thought to be the first for VC55

https://influentialpoints.com/Gallery/Monaphis_antennata_Solitary_birch_aphid.htm