Large clusters of these sturdy aphids inhabit the Meadowsweet (Filipendula ulmaria), probably Macrosiphum cholodkovskyi [1].

References
1 InfluentialPoints.comMacrosiphum cholodkovskyi
Filipendula ulmaria (Meadowsweet)Large clusters of these sturdy aphids inhabit the Meadowsweet (Filipendula ulmaria), probably Macrosiphum cholodkovskyi [1].
References
1 InfluentialPoints.com