To you, my leaf is a beautiful, floating pad, a decorative feature in your pond. To me, it is a vital organ, a solar panel and a lung. Each leaf is a factory where sunlight, water, and carbon dioxide are transformed into the energy that fuels my growth and the production of my magnificent flowers. When holes appear in my leaves, it is more than a cosmetic flaw; it is a direct assault on my ability to thrive. The integrity of my surface is crucial for photosynthesis and for preventing water from flooding my air-filled tissues, which keep me afloat. The culprits are often insects, and from my rooted position, I can only endure their feeding, but I can tell you exactly who is likely responsible based on the evidence they leave behind.
If the damage you see consists of neat, U-shaped notches taken out of the edges of my leaves, you are looking at the work of the Water Lily Beetle in its adult form. These small, brown beetles are deceptively charming but voracious. They do not merely punch holes; they systematically graze along the margins. This is particularly damaging because it reduces the overall surface area available for capturing sunlight. Before becoming these leaf-notching adults, their larvae were even more destructive. The yellowish, slug-like larvae feed on the upper surface of the leaf, creating winding trails or "windowpanes" by skeleto nizing the tissue, eating the green chlorophyll-rich cells and leaving the translucent lower epidermis intact. This type of damage severely impairs my photosynthetic capacity.
When you observe a cluster of small, soft-bodied insects, typically black or brown, on the stems and undersides of my leaves, you have found the Water Lily Aphid. While they themselves do not chew holes, their feeding activity is the primary cause. They pierce my skin with their needle-like mouthparts and suck out the nutrient-rich sap. This weakens the leaf tissue, causing it to yellow, curl, and become generally stressed. The real damage, however, often comes next. A black, sooty mold fungus grows on the sticky "honeydew" waste that the aphids excrete. This black coating further blocks sunlight. The combined stress from sap loss and light deprivation causes the leaf tissue to die in patches, which eventually fall out, creating a random pattern of small, irregular holes that can resemble a shotgun blast.
For the most dramatic damage—large, ragged holes or even entire sections of leaf missing—look for the China Mark Moth. The adult moth is harmless to me, but its aquatic caterpillar is a leaf miner and consumer. The female moth lays her eggs on my surface, and upon hatching, the small caterpillars burrow between the upper and lower surfaces of the leaf. They mine their way through the soft inner tissue, creating irregular blotches. As they grow larger and bolder, they emerge to feed openly from the upper surface, chewing large, unsightly holes. They are unique in that they often create a protective case by cutting two oval pieces from my leaf, binding them together with silk, and hiding inside as they feed. This is a clear sign of their presence.
As a plant, I am not entirely helpless. I can produce secondary compounds that make my leaves less palatable to some pests, and I will attempt to grow new leaves to replace the damaged ones, though this consumes a significant amount of my stored energy. You can assist me in this struggle. Regularly inspecting the undersides of my leaves and physically removing beetles, larvae, and aphid clusters can be highly effective. For aphids, a strong jet of water can dislodge them. Encouraging a balanced ecosystem in your pond by providing habitats for beneficial predators like ladybugs, lacewings, and aquatic beetles is the most sustainable long-term solution. These natural allies will help keep the leaf-eating insect populations in check, allowing me to focus my energy on what I do best: growing and flowering for you.
