What Is That … on the Lily Pad?

Waddells

We often enjoy ‘Monet moments’ walking or paddling along the shoreline, taking in the beauty of the masses of lily pads we find in sheltered bays near our cottage.

One can understand Monet’s repeated attempts in his more than 250 paintings of lily pads to capture the beautiful play of light on these tranquil scenes.  Not only are the large flat floating leaves and unique blossoms interesting to look at but so too are the many creatures one can observe on them.  Lily pads provide shelter from flying predators and intense sunlight for fish and other creatures living under water.  They serve as platforms for numerous insects, and provide food for plant-eating fish, insects, molluscs, waterfowl and mammals.

There are two readily identifiable species of large lily pads common in White Lake, the yellow pond lily and the white water-lily.  Both species are found in calm or slow moving water and typically sunny locations.  These perennial plants grow from rhizomes that over-winter in the lake bottom.  The leaves and flowers grow to the surface on long stems from the rhizome.  The white water-lily has round leaves with a narrow V-shaped notch while the leaves of the yellow pond lily are more heart shaped.  Both plants bloom from June to September.  You can guess the colour of their flowers.

Our first beastie uses water lilies as a platform. There are six species of water strider common in south-eastern Ontario.  These slender, dark brown to black insects can be seen  ‘skating’ over the water using their long second and third pairs of legs to stay afloat while capturing prey using their shorter forelegs.  While they are small, ranging from 10 to 25 millimetres in length, they are effective predators feeding on insects and other creatures in or on the water, including mosquito larvae (yeah).  Water striders can occasionally be seen resting on or hopping onto and off lily pads.  This photo shows a water strider resting on a lily pad.  The tiny red spots and the small beige creature are parasites.

The vesper bluet damselfly, which makes extensive use of lily pads as platforms, is common at our cottage.  The combination of yellow-orange thorax and blue abdomen tip makes this species easy to identify.  Males are attracted to lily pads where they perch.  Mating can occur on lily pads as shown in the following picture.

Eggs are laid on various aquatic plants near or on the water surface, including the top of lily pad leaves as shown in the next image.

After the eggs hatch, damselflies spend the larval stage of their life underwater, where they are voracious predators, undergoing numerous molts as they feed and grow.  Once ready for metamorphosis into an adult, the larvae crawls up onto the top of the lily pad leaf where the new adult (teneral) emerges through a split in the back of the thorax of the soon-to-be-exited larval case.  The teneral rests on the larval case as it pumps fluid to extend its wings before being able to fly.

The chestnut-marked pondweed moth and the waterlily borer moth are just two of the many aquatic crambid moths whose larvae feed on water lilies and other aquatic vegetation.  The adults are small, ranging in size from eight to 16 millimeters.  The first picture is of a chestnut-marked pondweed moth sharing a lily pad with a damselfly teneral and the second is of a waterlily borer moth resting on a lily pad.

The next time you are taking in calm scenes of lily pads floating in sun-drenched waters you may want to take the time to look closely at individual leaves and blossoms to appreciate better the diversity of beasties making use of the exposed portion of lily pads.

Several of the documents used in preparing this article include Timothy Dickinson et al The ROM Filed Guide to Wildflowers of Ontario; Canadian Wildlife Federation’s Shorelines … a festival of life; Dennis Paulson’s Dragonflies and Damselflies of the East; David Beadle & Seabrooke Leckie’s Peterson Field Guide to Moths of Northeastern North America; and, Tom Murray’s Insects of New England and New York.