CRITTERS AT
BBSP AND ELSEWHERE Water Insects
This page was born 10/11/2024. Rickubis designed
it. (such as it is.) Last update: 11/08/2024
Images and contents on this
page copyright © 2002-2024 Richard M. Dashnau
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This page features
insects that live and hunt in (and on) water. I'm including
insects that have a larval or nymph stage that lives in water,
although
the adults might not (such as dragonflies). The most recent
events will be at the top of the page, with older observations
as you move down. I
was inspired to create this page because of research I did
recently (2024) about water bugs. The picture above shows our
collection table
during a pond life program on the Spillway Trail in
2019--featuring an assortment of water insects (which all happen
to be true bugs!) and a few other
animals (freshwater shrimp, tadpole).
On
10/20/2024
I helped with another Pond Life Program, and we found a few water
bugs. These are Lethocerus species (I can't tell which one). The
last image shows an adult and a nymph-
they weren't staying together-I just happened to take the picture
when they moved by each other.
The first image below was
taken outside on the program table. The second image was taken inside the
Nature Center, after all the captures were put into the aquarium display.
They are nymphs, also. I believe they are nymphs because they don't have
wings, and Lethocerids because of their size. The third image shows one of
the Lethocerid nymphs nest
to a an adult of a different species of Giant Water Bug--a Belestoma
species. Both of them had their snorkels at the surface. Note the one on
the left has wings, and also has a point on
the tail end. The 4th image shows the Belestoma adult swimming by the
Lethocerid. Quite a size difference, there! Note the longer
"snorkel" on the Lethocerid. The other creature is a
dragonfly nymph.The fifth image shows a Belestoma out of the water,
feeding on a dragonfly larva.
There's one more thing. Although we can
see water bugs breathe air by putting their back ends to the surface
(that's where their snorkels are)--a few species carry air
back under water
with them. One species carries a bubble under its wings and over its
spiracles. Another uses a small trapped air bubble as a gill--by
moving its wings, which changes compression of the
bubble, and induces diffusion of gases of the water to and
from the air held inside the bubble! That is-oxygen
diffuses in, and carbon dioxide can diffuse out. Holy cow! (2011
goforth)
09/29/2024
At Brazos Bend State Park, I noticed something large caught in a spider
web on
the North loop of 40 Acre Lake trail.It was a Giant Water
Bug!
I couldn't get too close because the web was over the water. I only got a
few pictures. The spider seems to be a Tropical Orb weaver
(Eriophora ravilla). The insect was a really
big "giant water bug". Various sources describe them as highly
effective predators-feeding on many kinds of invertebrates and vertebrates!
Yet, this bug was subdued by a
smaller arthropod (the spider), aided by the technology of the spider's
web. I consider the web "technology" because it was built by the spider,
and is maintained by the spider
for its use. A vertical orb web contains 3 different types of thread which
comes from 3 different types of silk gland. And one of those threads is
made sticky by glue from a fourth
type of silk gland. An orb web can disperse the force of a flying
object by stretching in the direction of motion, and then moving back into
shape, with the object immobilized and
glued in place.(from the book, Spider Silk by Leslie Brunetta and
Catherine L. Craig ©2010) Sounds pretty technological to me.
But...I'm talking about the prey this time--the Water Bug.
I was inspired to learn more about Giant Water Bugs. After 19 articles, I
discovered many amazing things. The information below is mostly from these
4 sources. They have
summarized much of the information in the other studies:
1)
2009_Identifying American Giant Water Bug Genera _Goforth_
2) 2011 Subsurface
behaviours facilitate respiration by a physical gill in an adult
giant water bug, Abedus herberti by Goforth et al
3) 2016 Venoms
of Heteropteran Insects: A Treasure Trove of Diverse
Pharmacological Toolkits by Walker et. al.
4) 2018 Ecology of giant water bugs (Hemiptera:
Heteroptera: Belostomatidae) by Shin-ya Ohba
When I've assisted with the Pond Life programs, I've wondered about the
term "giant water bug" as it applied to the different-sized ones we
caught. "Giant water bugs" are an
entire family of insects (Belostomatidae), including about
150 species. It contains two subfamilies: 1)Belostomatinae
2)Lethocerinae. I believe we've encountered Giant Water
Bugs from both of those families during our pond life
programs. The ones that have always impressed me (and they include the
largest species) are in Lethocerinae.
One of those was caught in the web this morning. Bugs in Belostomatinae deposit
their eggs on the males' back. Those in Lethocerinae deposit their eggs
on emergent plants.
From Ohba 2018: "Belostomatinae does
not digest vertebrates well, because the saliva does not have
enzymes capable of digesting protein-rich meals such as vertebrate
animals."
"Lethocerinae, the largest-bodied subfamily in
Belostomatidae, prefer to eat mainly vertebrate animals
such as fish and anurans. For example, Lethocerus americanus prefers
to
eat larger fish." some researchers observed Lethocerus
attacking birds and water snakes. In recent years, it has also been
reported that K. deyrolli eats snakes and turtles in their
habitats in Japan. Therefore, giant water bugs should be
regarded as higher consumers of wetlands as well as vertebrate
predators."
So these
insects can feed on animals all over the food chain. Water bugs are in
the order Hemiptera (true bugs), distinguished from other insects
mostly by their mouth parts. The
mandibles and maxillae (which we can easily see in other insects) also
exist in true bugs, but are modified to form a "beak" with a
complex structure including separate tubes that
allow for application of venom/enzymes and ingestion of
liquefied food. And--true bugs are venomous.
from
Walker 2016:
"Venom is a secretion, produced in a
specialized gland in one animal, and delivered to a target animal
through the infliction of a wound. A venom must
further
contain molecules that disrupt normal physiological or
biochemical processes so as to facilitate feeding or defense
by the producing animal. Unfortunately, there is a historical
tradition among entomologists and venom researchers to confuse or
discount the venomous nature of heteropterans."
"Envenomation typically occurs in a swift strike in which the
mandibular and maxillary stylets penetrate the food source and venom
is injected, sometimes accompanied by grasping
or gripping with the forelegs or fore- and mid-legs.
Within this quick movement the sheath-like labium, its tip covered
with chemo- and mechanoreceptors, is pressed to the surface
of the food source; the pointed tips of the mandibular
stylets extend to cut into the prey and anchor it to the predator; and
the maxillary stylets extend into the prey, injecting venom.
Once venom injection has induced paralysis or death,
feeding typically occurs over a period of several minutes
to several hours. During this process the stylets may extend deep
into the prey, distributing liquefying venom, macerating the
prey, and sucking up fluid food. Some giant water bugs
(Belostomatidae) grow to be very large(10–12 cm) and have been
recorded killing vertebrates including frogs, turtles, snakes
and birds."
The term "extra-oral digestion" (EOD)
refers to the application of chemicals to allow for predigestion
(liquefying, etc.) before ingestion of the resultant "slurry". The various mixtures of
"salivas" and "venoms" are not consistent between all members of the
true bugs but are related and develop with the dietary
needs of each species. Depending on species, some of
these elements cause paralysis or death; immobilizing prey
allow for the other gland contents to break down the prey for
ingestion. There's a lot going with our insect neighbors. Here
are a few characteristics to help tell the species apart.
from Goforth 2009:"The
Abedus doesn’t have the long respiratory siphons you find in some
water bugs. These are called air straps, the shorter of the two
types of respiratory appendages
in the belostomatids. This bug is broadly rounded, particularly
in the back. The other two American genera of giant water bugs
have pointed tips at the end of their abdomens. So, the
combination of the rounded back end and short air straps lets
you know that this waterbug belongs to the genus Abedus. This bug has air straps and not the
long respiratory siphon.
Belostoma is more rounded overall than Lethocerus as well, but it is
also pointed in the back. You can tell Belostoma apart from
Lethocerus easily by looking at the size of the bug and
the presence of air straps. Belostoma is easy to distinguish from
Abedus simply by looking at the shape of the back end--pointed in
Belostoma and rounded in Abedus. Lethocerus is very
different from the Belostoma and Abedus. There's a long respiratory
siphon at the back end. They do look quite a bit shorter when
they’re retracted, so the difference between the respiratory
siphon of this bug and the air straps of Abedus should be
immediately obvious. The shape of Lethocerus is also distinctive.
This bug is robust and strong, has huge raptorial forelegs and
is also pointed at the back end. Lethocerus species are BIG
bugs."
So, we have at least 2
species of giant water bugs turning up at our pond life
programs. The biggest ones are Lethocerids (including the one I found
in the spider's web). I
had started looking
mostly for descriptions of the saliva/venom because I often wondered
they hurt so much if they bite and what they are putting into
us when they bite. I found all of this other material
during my
search.
06/11/2023
Brazos Bend State Park. As I was beginning to lead the Creekfield Hike
that morning, I was talking to our park guests when I looked over towards
the bathroom
doors. Sometimes, I take the group around the outside of the Nature
Center to look for whatever critters might be on the walls. That morning,
I was on the sidewalk when I saw
this very large insect near the door to the Breezeway. It was a Swamp
Darner (Epiaeschna heros), one of the largest dragonflies in the U.S.
After a brief online search, I found
that this species deposits its eggs by drilling into wood. This is
unlike many other dragonflies, which lay their eggs on water. The SD
stayed there while we got closer and
took pictures, and was still there about an hour later when I got a few
more pictures.
August
11, 2019 One of the most enjoyable programs we offer
at BBSP is the "Pond Life Program". We set up a "reservoir" table that can
hold water, and a flat table, on one of the
trails. We put water in the reservoir, then use nets to
collect samples of the aquatic vegetation. We place samples on the flat
table, and dig through them with tweezers to see what
we find. We put the live animals into the water for display and
description. After the program, many of the animals go into our display
aquarium in the Nature Center. Park visitors are
welcome to watch, or even assist with some loaner tweezers. Today was
quite productive. In the larger image, we can see small fish, freshwater
shrimp, crawfish, snails, water bugs,
and water scorpions (which are also "true bugs") I've labeled various
types of organisms we found during that Pond Life Program.
--
But the prize, in my
opinion, was the capture of these giant water bugs. I've always known they
were impressive predators, and it was a treat to see
them. I took all of these pictures with my phone. When I'm helping do the
program, I don't have time to handle my usual cameras. But I had to get
some pictures of these, showing details of the top and bottom views while
I held the bug.
--
December 05, 2004 There
are often interesting things to see in the aquarium at the NC. Today, on
of the Giant Water bugs had climbed out of the
water. Again, those eyes are amazing...and, that front pair of mighty
raptorial arms. (note: I'm
uploading these images 10/11/2024. I was previously
reluctant to share images I've gotten from the tank because they
aren't "in nature". Now, 20 years later, I know that sometimes there
is no other
option for seeing some of these creatures doing anything, except for
watching them inside an aquarium. )
---
November
14, 2004 There are often interesting things to see in
the aquarium at the NC. Today, multiple Giant Water bugs, with one that
was probably
eating one of the Water Scorpions. It was holding onto one its front
raptorial legs, and eventually a few of its other ones. (note:
I'm uploading these
images 10/11/2024. I was previously reluctant to share images I've
gotten from the tank because they aren't "in nature". Now, 20 years
later, I know that
sometimes there is no other option for seeing some of these creatures
doing anything, except for watching them inside an aquarium. )
---
September 19, 2004
Today, I took was able to get just on good picture of this Giant Water Bug
in the Nature Center. Getting clear images by shooting
through the glass is often difficult, but here's one. Look at those eyes!
(note: I'm uploading these images
10/11/2024. I was previously reluctant to share images I've gotten
from the tank because they aren't "in nature". Now, 20 years later, I
know that sometimes there is no other option for seeing some of these
creatures doing
anything, except for watching them inside an aquarium. )
August 29, 2004 There
is a big aquarium in the Nature Center. It is usually
stocked with animal life that we catch inside the park.
Usually, there are interesting things
to see in the aquarium. Today, I took was able to get some
good pictures of this Giant Water Bug. (note:
I'm uploading these images 10/11/2024. I was previously
reluctant to share images I've gotten from the tank because
they aren't "in nature". Now, 20 years later, I know that
sometimes there is no other option for seeing
some of these creatures doing anything, except for
watching them inside an aquarium. )
---
August 02, 2003l admit it. I
like some science-fiction. I like some science-fiction movies,
I like some movies with monsters, and some movies with alien
creatures that will come up upon
their unsuspecting prey and rip their head off.
But, you know what's
really, really cool? This kind of thing is happening on
Earth, in real life, all around me! And, unless you (my
internet guest
who's reading this) live somewhere like Antarctica, it's
happening all around you, too! To see it, all
you need to do is stop thinking all the time, take a mental
rest, and just look around.
The RICKUBISCAM today is
a picture of something that caught my attention when it moved
just at the edge of my peripheral vision. At first glance, it
looks like two dragonflies attempting to
make more little dragonflies. Then we can see that they appear
to be two different species of dragonlfly.
Then, if we take a closer
look (see THIS CAN'T BE GOOD, below), we can see that the
brown dragonfly (According to Park Naturalist David Heinicke,
the Green Dragonfly is a female
Eastern Pondhawk-Erthemis simplicicollis; the deceased one is
a female Widow Skimmer - Libellua lucuosa. Thanks, David.) is
missing its head and part of its thorax. A little bit closer
view
(see CONCEALED WEAPON, below) shows the mandibles slipping
from their wonderfully complex and mechanical sheath and
grinding away at the hapless victim. To see two short
clips
of the mandibles in action click on the following links clip
one (flv video 647kb, or see EATING 1, below); clip
two (flv video 658kb, or see EATING 2, below). (Sorry
about the movement of the
camera. I couldn't set up a tripod.) Now
we can see that this is the outcome of another intricate,
high-speed dogfight between two dragonflies. Those bozos!
Can't they cut that stuff out and
go after deerflies and mosquitos instead? There must be plenty
of those to go around! However, when you get to this level of
existence, you have prey animals, and then you have
animals
that you have to compete with for that prey, and you have
animals that might think YOU are prey. A dragonfly eating
another is not only giving itself more food by eliminating
competition; it's
getting a meal directly while it's eliminating the
competition! Not to mention that it's also eliminating a
potential attacker. Wait, I mentioned it. Oh, well.
---
GHASTLY EMBRACE
THIS
CAN'T BE GOOD
CONCEALED WEAPON
DRAGONFLY
EATING
1
DRAGONFLY
EATING2
July 27, 2003This is how I think it
happened:It glided silently through the jungle that was its
hunting ground. Among its fellow creatures, it was the apex
predator, and it moved its
delicate, sleek length through the clearings and passages of its
domain. From time to time, lesser creatures would become
visible, and many of them were attacked and killed in seconds,
and then chewed to pulp and eaten. Many times, this fearsome
predator wouldn't even bother to stop moving as it ate its
helpless victims. As a flier, it had no peer, and had evolved
a
fantastic behavior that would allow it to fly at prey (or
challenge others of its kind) by flying in a manner that--although
it was moving at a terrific speed--would allow it appear immobile
to its
intended target. Since it appeared to be a stationary
object, its intended target would ignore it; until it was too
late, and then another victim could die. The predator was a
Dragonfly--a Green
Darner. Its huge compound eyes covered its entire head, and it
could see in almost every direction simultaneously.
As it flew through a stand of
tall weeds (grass is common for what
happens next)--perhaps swooping for prey--there was a sudden
movement from above and behind. The dragonfly may have felt
a loud buzz, and suddenly it was hit from above, in the thorax,
right between the wings. Immediately after, a sharp spike was
thrust into the dragonfly's beautiful hard shell, and it lost
control of its wings. It hit the ground, and was already helpless
as its
bodily fluids began to be pulped and sucked out through a single
hole in its exoskeleton. The dragonfly was doomed.
The Dragonfly had been
attacked by a Robber Fly. These are large
insects that are *also* apex predators. They are also deadly and
efficient hunters. However, where the Dragonfly relies on strength
and speed, and can fly and attack in the open, the Robber
Fly will often perch on a good spot (like a tall blade of grass)
and just watch. When something interesting passes, the Robber Fly
launches its surprise attack, and hits its prey in flight. Where
the Dragonfly chews its prey to pulp with its mandibles, the
Robber Fly uses piercing mouthparts to suck out juices.
The image below (IN ITS
CLUTCHES, below) shows the outcome of the
hunt. I've seen Robber Flies hunting, just as I've described.
Often, they just fall to the ground (although it seems they try to
brake with their wings) with their prey. I have been trying to get
some
good close-ups of this for at least a year, but the insects have
always flown off. This morning, however, one of the
volunteers (cool, Allen!) just walked into the visitor center with
the Dragonfly
and its killer. The Robber Fly was attached, eating, and
would NOT move. I snapped a few pictures. The pair of
insects was then left outside, where I was able to get some better
close-ups.
The three pictures below are three views of the same image.
The fingers are mine, and you can see the scale. I've cropped in
to show the mouthparts where it pierces the thorax. Later
in
the day, the Dragonfly was still in the garden and was intact,
though reasonably empty. Ants had found the carcass, though (lots
of ants...FIRE ants. No more pictures. Sorry.). And the Robber
Fly had gone; perhaps to attack another Dragonfly, perhaps to be
eaten BY a Dragonfly.
------
IN ITS CLUTCHES
LLET ME EAT IN
PEACE
KILLER AND
VICTIM
NEAT EATER
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