Predation
All insect's share two basic traits for avoiding being killed by a predator, behavioral
modification and morphological defense. But like everything else, things go wrong
that make the insect vulnerable to predators. While most adult dragonflies
are alert and fast enough that they are seldom captured by predators they can be
very vulnerable as tenerals or when chilled in the early morning. It is common
to observe a teneral on its maiden flight get snatched up by a Catbird, Flycatcher
or Waxwing. Frogs will gulp down the unwary ode that gets too close, and herons
have been observed snatching one teneral after another from the edges of ponds during
mass emergences.
A number of dragonflies routinely catch and dine on damselflies or another dragonfly,
sometimes even their own species. This is also common among the damselflies.
Other insects such as wasps and bees have also been known to harm odonates.
While I was photographing a perched Swamp Darner (right) a single wasp popped up
from nowhere, circling the darner repeatedly and stinging it until it fell to its
death. The wasp neither ate it or carried it off. The reason for such
behavior I have yet to find out.
Spider webs are a common hazard to odonates, especially damselflies and teneral
dragonflies who are not very strong fliers. Many of them accidentally fly
into webs; if unable to free themselves they are destined to be dinner for a hungry
spider.
Carnivorous plants such as sundew may trap the unwary damselfly with their sticky
leaves. The gooey liquid which the leaves produce ultimately breaks down body
tissues in the ode which is slowly digested by the plant.
Odonate larvae are not immune to predators. Although equipped for rapid locomotion,
they sometimes falls prey to fish, frogs, toads, newts, ducks and others.
If that's not all, odonate eggs also have predators. Fish and other insects
find odonate eggs quite a delicacy. Small parasitic wasps swim through the water
searching for odonate eggs. The wasps lay their own eggs on each dragonfly egg,
when the wasps eggs hatch, the wasp larvae eats the contents of the dragonfly eggs.
Less obvious enemies of odonates are parasitic red or green mites that gather in
clumps resembling little beads on the underside of the thorax and abdomen infiltrating
body tissue, causing irritation or infection. If too many are present they
may also cause an instability during flight. Parasitic infestations are for
some reason more common in the pond dragonflies, notably the Skimmer Family (Libellula).
Another bothersome culprit is a biting gnat which attaches itself and sucks blood
from the wing veins eventually weakening the insect.
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