Dragonflies and Damselflies of Eagle Lake & Eastern Ontario
It all started again on a walk along the Southshore Lane at Eagle Lake one
sunny warm morning in late June 2012: A rekindled interest in local
dragonflies. Camera in hand, it soon became evident that dragonflies were
numerous that day, darting about or perched on branches and the road
surface.

Within one and a half hours, I had photographed what I thought were 13
different species. What I learned later was that in many species male and
female dragonflies differ in wing and body markings and general coloration. In
reality, eight species were photographed that morning. Since then, additional
species--some with quite striking wing patterns--have been observed in our
locale (see figures on this page). By the summer of 2015, 26 species of
dragonflies and 12 different damselfly species had been identified.
Photographs by Sandy and Irv Dardick
The larva of mayflies, stoneflies,
damselflies and dragonflies are
excellent predicators of lake and
stream water quality. A variety of
pollutants cause an early marked
decline or absence of such insect larva
and so can signal a decline in the
health of a lake. At Eagle Lake,
perhaps there is another potential
threat to the dragonfly and damselfly
populations, the invasive aquatic plant
European frogbit. Not only do the
dense mats formed by European
frogbit block sunlight and alter the
lakebed at the shoreline for aquatic
insects, but the decomposing
vegetation from this plant in the fall
can reduce oxygen levels sufficient to
kill dragonfly larva. So it is essential to
remove as much as possible of this
invasive plant.
Adult and nymph (the aquatic larval
phase) dragonflies eat mainly insects
of considerable variety (nymph diet
can also include tadpoles and small
fish). Since their diet consists of a
good proportion of both larval and
adult mosquitoes, dragonflies are
quite beneficial in cottage country. As
a further statement of their value, it
has been suggested that they can eat
food equivalent to their own body
weight in 30 minutes. Quite a dietary
feat! So they and their aquatic habitat
need to be protected.
Twelve-spotted Skimmer, female (Libellula pulchella)
Fortunately, however, there appears
to be numerous dragonflies and a
reasonable number of different
species at Eagle Lake. In the Ottawa
region, the Ottawa Field Naturalists
Club has recorded 120 species of
dragonflies and damselflies. To date,
40 species have been identified at
Eagle Lake. Links to these species are
provided at the top left.
Halloween Pennant (Celithemis eponina)
References:
Dunkle SW: Dragonflies through Binoculars, A Field Guide to Dragonflies of North
America. Oxford University Press, 2000.

Paulson, D: Dragonflies and Damselflies of the East. Princeton University Press,
2011.
Orange bluet (Enallagma signatum) and Northern Bluet (Enallagma annexum) Damselflies
As a major predator in the insect world, dragonflies are a successful, ancient
species. Fossil records of dragonflies date from 300 million years. One can
only wonder what the food source was for that largest fossil dragonfly with a
wingspan of 2.5 feet (0.76 metres).
Copyright © Irving Dardick 2017
eaglelake@bell.net