Waterlilies can be fed upon by several invertebrates, all tend to be sporadic and damaging populations do not usually occur year after year.

Waterlily aphid, Rhopalosiphum nymphaeae is a small (1.5-2.5mm) reddish brown or dull green aphid. It sucks

Sap is a fluid that circulates through a plant's vascular system, in a similar way to blood moving through our veins. Phloem sap carries the sugars produced in the leaves by photosynthesis down to roots and other storage organs, as well as carrying minerals and hormones. Xylem sap is watery and transports nutrients absorbed by the roots upwards to the rest of the plant. Some plants leak sap from wounds or pruning cuts, and this is known as bleeding.

Water lily beetle, Galerucella nymphae is a 6-7mm long greyish brown beetle. The adult and its black grubs feed on foliage and flower

A bud is a small, undeveloped shoot that contains the potential for new growth. Buds are typically found on stems, where they can be apical (found at the tip) or axillary (found between leaf axils) and may develop into leaves, shoots or flowers.

Brown China mark moth, Elophila nymphaeata is one of several moths that have aquatic caterpillars. The adult moth has a wingspan of 20-30mm and is variable in wing colouration, most often being brown with white spots. The caterpillars of this and some closely related species feed on a range of aquatic plants including waterlilies. Initially the caterpillar forms a leaf mine but later stages feed under a fold of leaf material. As with waterlily beetle affected leaves can rot and disintegrate. Adults can be found in July and August, caterpillars can be found throughout the year.

Chironomid midges are a family of flies many of which have aquatic larvae. The adults are gnat or mosquito like, although they do not bite. Usually the slender larvae (maggots) feed on decomposing matter at the bottom of ponds. They will however, feed on waterlilies that have begun to rot due to other causes, such as waterlily beetle damage. Occasionally chironomid midges are the primary cause of damage this tends to happen only in new ponds and water features. These insects are present throughout the year.

Pond snails. Most pond snails do not damage healthy plants preferring to feed on decomposing plant matter and algae. They do however, often lay elongate (approx. 2cm) gelatinous egg sacks, on the undersides of waterlilies.

• Waterlily invertebrates are difficult to manage and in most cases must be tolerated. Most of these animals are sporadic and do not usually occur every year on the same patch and the waterlilies recover.
• Waterlily aphid and beetle can be wiped off the leaves and buds. This is feasible on small ponds where the lily leaves are within reach from the sides of the pond. They often have to be tolerated in larger ponds
• None of the insecticides available to home gardeners can be used in a pond or water feature, because of the danger to fish, amphibians and all other forms of aquatic life