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Flying insects are usually
creepy, but many people love dragonflies. (Courtesy of Flickr
user whologwhy)
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Flying insects are usually annoying. Mosquitoes
bite you, leaving itchy red welts. Bees and wasps sting. Flies are
just disgusting. But theres something magical about dragonflies.
1 ) Dragonflies were some of the
first winged insects to evolve, some 300 million years ago. Modern
dragonflies have wingspans of only two to five inches, but fossil
dragonflies have been found with wingspans of up to two feet.
2 ) Some scientists theorize that high
oxygen levels during the Paleozoic era allowed dragonflies to
grow to monster size.
3 ) There are more than 5,000 known
species of dragonflies, all of which (along with damselflies) belong
to the order Odonata, which means toothed one in Greek
and refers to the dragonflys serrated
teeth.
4 ) In their larval
stage, which can last up to two years, dragonflies are aquatic
and eat just about anythingtadpoles, mosquitoes, fish, other
insect larvae and even each other.
5 ) At the end of its larval stage,
the dragonfly crawls out of the water, then its exoskeleton cracks
open and releases the insects abdomen, which had been packed
in like a telescope. Its four wings come out, and they dry and harden
over the next several hours to days.
6 ) Dragonflies are expert fliers. They can fly
straight up and down, hover like a helicopter and even mate mid-air.
If they cant fly, theyll starve because they only eat
prey they catch while flying.
7 ) Dragonflies catch their insect
prey by grabbing it with their feet. Theyre so efficient in
their hunting that, in one Harvard
University study, the dragonflies caught 90 to 95 percent of
the prey released into their enclosure.
8 ) The flight of the dragonfly is so special that
it has inspired engineers
who dream of making robots that fly like dragonflies.
9 ) Some adult dragonflies live
for only a few weeks while others live up to a year.
10 ) Nearly all of the dragonflys head is
eye, so they have incredible vision that encompasses almost every
angle except right behind them.
11 ) Dragonflies, which eat insects
as adults, are a great control on the mosquito population. A single
dragonfly can eat 30 to hundreds of mosquitoes per day.
12 ) Hundreds of dragonflies of different species
will gather in swarms, either for feeding or migration. Little is
known about this behavior, but the Dragonfly
Swarm Project is collecting reports on swarms to better understand
the behavior. (Report a swarm here.)
13 ) Scientists have tracked
migratory dragonflies by attaching tiny transmitters to wings
with a combination of eyelash adhesive and superglue. They found
that green darners from New Jersey traveled only every third day
and an average of 7.5 miles per day (though one dragonfly traveled
100 miles in a single day).
14 ) A dragonfly called the globe
skinner has the longest migration of any insect11,000
miles back and forth across the Indian Ocean.
Overview
of Odonata
Dragonflies and damselflies are part of the order Odonata (odonates).
Insects of the order Odonata are divided in two suborders:
Epiprocta (dragonflies) and Zygoptera (damselflies).
Dragonfly
External Anatomy
What
is a dragonfly?
Living on every continent but Antarctica, these insects are instantly
recognizable by their large bodies; four long, horizontal wings;
and the way they hover and zip around. Dragonflies can reach speeds
of up to 35 miles an hour and fly just as gracefully backward by
lifting off vertically, helicopter style. Their compound eyes are
so large they nearly touch, and each one has about 28,000 single
eyes, or ommatidia.
https://www.nationalgeographic.com/animals/invertebrates/d/dragonflies-insects/
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