Pond pests found eating waterlily leaves:
1. China Mark Moth
- Look for large, neat holes on the edge of your waterlily leaves.
- The caterpillar will cut holes in the leaves on the edges or centrally where the stem joins the leaf.
- These pieces will be placed on the underside of the leaf to cover the pupa. Each develops under its own patch of bitten off leaf.
- Lift off the patch to expose the pupa. To control an infestation you should destroy the pupa.
- Remove all the affected leaves and burn them.
- You do not find the adult doing this but you are removing future generations so this is a long term plan.
2. Pond Snails
- The Great Pond Snail - (the pointed shelled snail not the circular shell of the ramshorn snail) will eat waterlily leaves.
- Above is a photo of the jelly capsules of snail eggs on the back of a waterlily leaf.
- Remove the egg capsules from the leaf with a thumbnail to keep the population under control or remove the whole leaf to the compost bin.
- To remove snails from your pond - float a juicy lettuce leaf on the water surface overnight. Next morning carefully lift it off and you will bring with it lots of pond snails grazing happily.
3. Waterlily Beetle
- Water lily beetle - Galerucella nymphae
- The adult Waterlily beetle and its larvae eat long slit like holes in waterlily leaves or chew around the leaf edge - the adults are 1/4" long(5mm) and are yellow/brown.
- Adults emerge from winter hiding places in nearby foliage and are capable of flying. They lay small white eggs on the top surface of the waterlily leaves in May.
- Kill these eggs by drowning the plant leaves for a few days under the water. Or spray a dilute mixture of washing up liquid over the infected leaves. (10ml washing up liquid in 250ml water). Apparently a mix of cooking oil in water will do the same job
- The larvae and pupae are black - thin and 5mm long and can be seen on the top of the leaf eating into the top surface to make the long, slit shaped marks in Summer.
- Waterlily beetle will disfigure the plant leaf and weaken it causing it to replace rotting leaf with new.
4. Waterlily Aphid
- Aphids also affect soft and succulent leaves of the water lily. They are minute - 2mm in size and brown/black & will suck the sap from the leaf.
- The adults and eggs overwinter on Prunus plants - Cherries, Plums and Blackthorn. They hatch in Spring until mid summer when they can fly to the waterlily plant.
- The leaf will become yellow and often distorted which allows the aphids to infest the underside of the leaf too.
- Drown the aphids by dropping the planted basket to the bottom of the pond for two or three days.
- Or spray the waterlily leaf with the detergent mixture described above and they will no longer be able to fly or mate.
- For better long term results spray the host tree in December with Winter Tree Wash by Growing Success or Vitax to reduce the number of overwintering eggs.
Check for these pests that are eating your waterlily leaves as part of your care for water lilies in Summer.