Deal with aphids organically: Method 4
Deal with aphids organically: Method 3
Deal with aphids organically: Method 2
Waterlily aphid is a species of true bug. They're sap-suckers, concentrating its feeding to the upper surfaces of leaves and the developing flower buds. They can be most damaging during optimal years, where dense colonies can begin to build upon the host plants. This aphid requires plants belonging to the Prunus genus to complete its life cycle. They'll migrate to Prunus during autumn to lay eggs. Those eggs hatch in spring, with adults migrating back to waterlilies in the early summer.
Its believed these aphids can transmit plant viruses.
Populations tend to be sporadic, only being damaging some years.
These aphids are soft-bodied, reaching 2.5mm long. They tend to be broader compared with other aphids, and they're brownish-green in colour. They form dense colonies on areas of new growth in plants, including near developing flowers. Adults can be winged, or wingless. Nymphs are generally smaller in size, paler, and lacking wings.
Dense groupings of the aphids can rapidly develop on the underside of the hellebores leaves. The aphids can form mutually beneficial relationships with ants, which eat the sugary honeydew that aphids excrete. Ants will protect aphids from predators and this can enable aphid populations to expand quickly.
Unfortunately, waterlily pests are difficult to control, so should be tolerated. Damage is often sporadic, with some years being worse than others.
You can't use pesticides near any waterbody because they're extremely toxic to aquatic wildlife.