Dragonflies, Bats, and Purple Martins

Educating the Public:
Dragonflies, Bats, and Purple Martins
Steve Robertson
Command Entomologist
HQ ACC/A7OO
4 Feb 2015
Start By Waxing Philosophical
Ecclesiastes 1:
9 . . . there is no new thing under the sun. . . .
11There is no remembrance of former things;
neither shall there be any remembrance of things
that are to come with those that shall come after.
“The one who does not remember history is bound
to live through it again”
-- George Santayana
Inscribed on a plaque at the Auschwitz concentration camp
Commonly paraphrased:
“Those who forget history are doomed to repeat it.”
Public Perception
• Public believes lots of myths
– If someone says it, it’s the Gospel Truth!
– Then it spreads like wildfire
• It is our job to be the
Forever! Because the myths never die!
I know! The one
that’s about to
eat you!
What is the
most dangerous
animal in the
whole world?
I’m gonna need a
bigger sword!!!
The Mosquito
Anopheles quadrimaculatus
(Eastern) Malaria Mosquito
Anopheles gambiae
African Malaria Mosquito
Aedes albopictus
Asian Tiger Mosquito
Anopheles freeborni
(Western) Malaria Mosquito
Culex pipiens Complex
Common House Mosquito
Aedes aegypti
Yellow Fever Mosquito
“The mosquito is more dangerous than the tiger.”
-- Thai Proverb
Why Do You Have to Spray for Mosquitoes?
Don’t you
know that if
you’d just stop
spraying that
the . . .
Natural Pest Management
• The Perceived Big 3 Mosquito Predators
– Dragonflies
– Bats
– Purple Martins
I ain’t worried about
these jokers!
Dragonflies vs Mosquitoes
Both require water for immature stages
Dragonflies
• Long-lived
• Requires permanent
water source
– Immature stage takes
one or more years to
complete
Mosquitoes
• Short-lived
• Can take advantage of
permanent & temporary
water sources
– Mosquitoes have more
breeding habitats
– Temporary mosquito
breeding habitats are not
suitable for dragonfly
development
Dragonflies vs Mosquitoes
Aquatic Hangouts
• Mosquitoes
• Dragonflies
Dragonfly naiads
hang out on the floor
of the water source
Mosquito larvae and
pupae hang out at the
water’s surface
Dragonflies vs Mosquitoes
Generational Reproductive Rate
Dragonflies
• Single
generation/year
Mosquitoes
• Multiple generations/year
– Fast paced life cycle to take
– Several species take
advantage of temporary
My great, great,
2 or more years to
water sources
great, great, great,
complete life cycle
great, great, great
grandfather was
• Not able to rapidly
born in 1855!
increase their
numbers in response
to a build-up of a
multi-generational
pest
My great, great,
great, great, great,
great, great, great
grandfather was
born in 2007!
HA! My great, great,
great, great, great,
great, great, great
grandfather was born
ONLY 5 months ago!
Dragonflies vs Mosquitoes
Adult Activity Periods
Dragonflies are Diurnal
• Adults are active during
daylight hours
– Sun up to sun down
Mosquitoes are Nocturnal
• Most mosquito species
are active at night
– Dusk to dawn
Dragonflies vs Mosquitoes
• Dragonflies are Not Host Specific
– Opportunistic feeders
• Includes immature aquatic
stage and adults
• Flies, bees, butterflies,
moths, mayflies, midges,
mosquitoes, swarming
termites, etc., etc., etc.
• Even other dragonflies
Dragonflies vs Mosquitoes
When the Predator Becomes the Prey
• Dragonflies are also consumed by other
predators
– Fish
– Frogs
– Birds
– Other aquatic insects
– etc. . .
I’ll take a fat
dragonfly over a
skrawny skeeter any
day. Mighty Tasty!!!
• Dragonfly naiads are cannibalistic
Dragonfly vs Spider
When the Predator Becomes the Prey
Hampton, VA
Steve Robertson
So Where Does This
Research Come From?
Vectors & Vector-Borne Diseases in the U.S.
1890: life expectancy at birth between 42.5 to 45 years of age
Fine!!!
So What About Bats?
Page 179
Bats, Mosquitoes and Dollars
Dr. Charles A.R. Campbell, 1925
Bats, Mosquitoes
and Dollars
Dr Campbell’s
Malaria-Eradicating
Guano-Producing
Bat Roost
Charles A.R. Campbell
Introduction by
Ernest Thompson Seton
Municipal Bat Roost,
erected by the City Council
of the City of San Antonio,
Texas, March 17th, 1916
Bats Heralded as Answer to Mosquito Problems
State Office Offers Plans For Bat Houses
June 08, 1989|By CHARLES CLARY Staff Writer
JAMES CITY (COUNTY) — Consider a different way to get rid of those
nagging mosquitoes.
...
“Lab studies show that a single Little Brown
Bat, one of the species most common in the
northern two-thirds of the U.S. and Canada, can
catch 600 or more mosquitoes in an hour.”
...
• The Echolocation of Flying Insects by Bats
– Biological Laboratories, Harvard University
• Donald R. Griffin, Fredric A. Webster, Charles R. Michael
• Published in 1960: Animal Behavior, VIII, 3-4, pp. 141-154
– Research was on ECOLOCATION; NOT ON BAT DIETS!!!
– Bats were observed in the confinement of a room filled ONLY
with mosquitoes or ONLY with fruit flies
• Echolocated and ate ~10 mosquitoes/minute (extrapolated 600/hour)
• Echolocated and ate ~14 fruit flies/minute (extrapolated 840/hour)
– Unfortunately, this research is often MISQUOTED as saying
that bats eat 600 mosquitoes/hour
• Bats prefer larger insects like beetles, wasps, moths, & other large insects
• In nature, mosquitoes only make up about 1% of the bat’s diet
OK, OK, OK!!! But, those
purple martins will surely save us!
RIGHT?!!!
Female
Photo by Chris Bosak
Male
...
Purple Martins
• Purple Martin Conservation Association (PMCA)
– Founder: Ornithologist James Hill
• Martins eat an insignificant number of mosquitoes
• No more than 0 – 3 percent of their diet
• Prefer larger flying insects: June bugs, moths, bees,
wasps, butterflies, dragonflies, etc.
– Research done at PMCA in Edinboro, PA
• 7-year study
• Analyzed 500 diet samples from parent martins collected:
– All hours of day
– All season long
– Numerous habitats, including mosquito-infested habitats
• Results: Zero (0) mosquitoes found in the 500 samples
"The number of mosquitoes that martins eat is extremely insignificant, and they
certainly don't control them. In-depth studies have shown that mosquitoes
comprise no more than 0 to 3 percent of the diet of martins". -- James Hill
United States
Vectors
& Vector-Borne Diseases in the U.S.
West Nile Fever
1890 United
States population was 62,622,250
Summary:
1999 - 2014
Year
Cases
Deaths
2014
2,122
85
2013
2,469
119
2012
5,387
243
2011
712
43
2010
1,021
57
2009
720
32
2008
1,356
44
2007
3,630
124
2006
4,269
177
2005
3,000
119
2004
2,539
100
2003
9,862
264
2002
4,156
284
2001
66
10
2000
21
2
1999
62
7
41,392
TOTALS
1,710
Yellow Fever Park, Norfolk, Virginia
1855 – Yellow Fever Epidemic
~2,000 dead
~1,200 dead
Hampton Veterans Affairs Medical Center Cemetery
Hampton, Virginia
1898 – Yellow Fever Outbreak
End By Waxing Philosophical
“Nothing in the world is
more dangerous than
sincere ignorance and
conscientious stupidity.”
– Dr. Martin Luther King, Jr.,
Strength to Love, 1963
Questions
OK, you mythbusters:
Get out there and educate the public—
Bust Those Myths!
Steve Robertson - [email protected]
Sorry!
I cannot give you my work info because I’m changing jobs.
Next week I start work at the
Naval Facilities Engineering Command Atlantic (NAVFAC LANT)