Bush Mantis, a Photo Journal
Did I already mention that ever since
I was a kid I was fascinated with insects and that the ones that fascinated me the most
were mantises? Why yes, I believe I did.
The biggest and most common mantis in my area was the bush mantis
(Sphodromantis viridis).
that’s the reason I kept them as pets when I was younger, and was also why I decided to raise a few in 2011 and photograph their entire life cycle.
This is the
bush mantis’s Ootheca, it is made of foam, produced by glands in the female’s
abdomen.
The glands actually release a liquid substance that surrounds the eggs and it
only later turns into solidified foam. This foam creates a layer of physical protection
from possible predators, as well as protection from extreme humidity and
temperature conditions.
But the
ootheca’s protection is not perfect. Sometimes, the first insects to emerge from
the egg sack are not bush mantis nymphs, but adult wasps from the genus Podagrion. These are parasitic wasps that prey on the bush mantis’ eggs. An
adult female wasp uses its extremely long ovipositor to lay several eggs inside
the ootheca, bypassing the protection it provides. The wasp larvae hatch quickly
and start feeding on the defenseless mantis eggs, the larvae go through several
larval instars, pupate (since they are Holometabolous insects), and emerge as
adults from the mantis ootheca, long before the little mantids get the
chance to hatch from their eggs. These tiny wasps, which are no more than 4 mm
long, are probably the mantids' biggest and most deadly enemy.
Female Podagrion rearranging the ovipositor inside its sheath, while standing on an
infected ootheca, next to her exit hole.
A close-up on a female, shot with a reversed 50 mm lens mounted on top of a 100mm macro lens.
An ootheca
that was infected by a Podagrion wasp, showing the wasps’ exit holes,
These holes look different compared to the mantis’ exit holes and are usually
on different parts of the ootheca.
Hatching and instars
The luckier mantis nymphs, ones that either weren't in an infected ootheca or were in an infected ootheca but weren't eaten, hatch 30 days (if the temperature is around 25C/77F) to 70 days (if the temperature is around 10C/50F) after the ootheca was laid. When they hatch they still have an additional layer surrounding their bodies, which doesn’t allow them to use their legs, only to wiggle around as they break out.
that’s the reason they immediately spin a silk-like thread and while suspended in the air, they remove this layer and begin their first instar.
At this stage, they already look like a 7 mm, miniature version of the adults (since they are Hemimetabolous insects).
After a couple of days, they become a bit darker.
Different
mantid species can have a different number of instars, for the bush mantis it
usually takes seven to nine larval stages before they reach adulthood.
Second instar, 10 mm long.
A second instar mantis snacking on an aphid:
Close-up on a second instar mantis nymph.
Third
instar, 15 mm long.
Fourth instar, 20 mm long.
Fifth
instar, 25 mm long.
Sixth
instar, 30 mm long.
Seventh
instar, 40 mm long.
Eighth
instar, 50 mm long.
Ninth
instar, 60 mm long.
Molting
Like other arthropods, mantids need to molt in order to grow bigger. Their amazing exoskeleton offers great protection, but limits their growth, therefore, with each instar, they need to remove the cuticle layer of their exoskeleton, and while the new cuticle created by their epidermis is still soft, they inhale air and contract their muscles to become as big as they can, they then wait for the new cuticle to oxidize and harden. This will give them more room to grow until they’ll need to repeat this process with the next instar. The adult bush mantis mass is about 1000 times bigger compared to the newly hatched youngling, meaning that they more than double in mass with each instar. Similar to other insects, once they reach adulthood they stop molting and growing in size.
Before the
mantids molt, you can start noticing behavioral changes – they become less
active and refuse to eat. While it implies they’re about to molt, it’s still
not clear when exactly it’ll happen, a mantis might stop eating three days before it
actually molts. Since I wanted to capture this moment (and not to photograph it
through the plastic cover of the mantis enclosure), I’d take the mantids out when
I’d see these behavioral changes, and watch them for several hours at a time,
usually, nothing would happen while I'd let them out, only to come home a couple of days later and see
that the mantis molted when I wasn’t there.
I did get
to witness and document this small wonder once though.
Beginning
of the molt, we can start seeing the cuticle layer of the exoskeleton, as it separates from the epidermis.
The head
and the thorax are starting to come out.
The thorax,
the head, and the front legs are already out.
The tegmen,
while still folded.
The fully
spread tegmen.
A short
video showing part of the tegmen spread
The “new”
front legs.
Zoom out on
the whole process.
Adulthood
After the last molt, the bush mantis reached adulthood and is about 70 mm long.
Food
As the mantids grow, so does the size of their prey. The mantids that I raised ate tiny fruit flies right after hatching, went through cricket nymphs in various sizes, and
ended with adult crickets.
These insects are amazing in their own right and you can discover wonderful
things when you spend the time and watch them. I, for one, was very surprised
to find that my male crickets chirped when they were near other males, not when they were near females (as I would have expected). Seeing their wings move to create
the chirp is also pretty amazing. The fruit flies (Drosophila melanogaster),
which I used as food for the first instar nymphs, are one of the most studied
model organisms and were also the subject of my thesis.
A cricket
examining a piece of paper.
Mating and laying a new ootheca
About a
month after the female reached adulthood, it is ready to mate, now all we need
is a male. Mounting the bush mantis female can be a long and tedious process,
but can sometimes be extremely quick. Usually, the male approaches cautiously,
but once its antenna touches the female, it will mount the female immediately.
After mating
for several hours, it will take the female between a few days and a few weeks to
lay the ootheca, but in some cases, the female might lay it even on the same
day, which is what happened in our case.
When the female mantis laid the ootheca, she finished our story, which started when I found the ootheca she hatched from.
Bloopers and extras
When I took
the photos of the adult females, a Google tricycle passed by and took my photo taking a photo, pretty meta! You can now find me on google street view in two ways:
- The fun way: Play detective and find me using the photo alone (it's not that hard).
- The easy way: Click here
Taking
photos of mantids can be exhausting, the nymphs are very small and quick, but surprisingly, the adults, while looking big and clumsy, are also
extremely quick and will usually try to flee from the threat – your camera
lens!
Mantids are very aware of their surroundings, and their famous head tilts anthropomorphize them and are part of the reason people like them. Sometimes they won’t run away when you shoot them, but instead will look at the lens and then slowly move backward/sideways until they’re just out of the lens's view, they’ll then stop and wait. This can lead to situations that are as funny as they are frustrating. I’ll end this blog post with a few.
Thanks
I’d like to thank Amir Weinstein for providing me with useful information and literature about Sphodromantis viridis, Barak Levi for being a great guy and always being willing to share the crickets he raised in order to feed my mantids, and my dad for taking the first photo here, keeping the text I wrote a while ago and thought I lost forever, and for encouraging my fascination with nature since I was little.