HIERODULA Grandis eyes problems

[mr nick]

I noticed that black spots appear after keeping mantids for some time (about 10 hours) in small containers (around 2 mantid's length), usually when transporting them. I think this is a stress reaction caused by lack of space.

I too have noticed that too,but my theory is that it is down to artificial light...i had a sub-adult Grandis nymph that developed a spot on one eye which disappeared on the final moult..

 

[vafan13]

Me too. Not pretty, but they look like they can inflict a (relatively) large amount of violence. Much like, say, an A-10 "Warthog".Man, I want one.

Mine got similar dark spots within one day of being in his container (as opposed to being free to roam about a large screened in porch). I watched him quite a bit (cage is next to my computer). I never once saw him ram the plastic sides head first, he would just scratch at them with his forelegs until he realized he wasn't getting through. then he'd settle down and chill, hanging from the top.

 

[Borya]

L 12 cm x L 12 cm x 30 cm high

Thanks. Are the glass terrariums larger?

I think it is quite small for 6-7cm mantis, especially for slim adult ones (but may do well for larvae, because of their abdonem is turned up). In my opinion, each dimension must be at least 3 mantid's length.

Usually black spots appear just one day after replacing a mantis from large terrarium (or if they live without any terrarium, on potplants) into small one. Mantids who live in small containers (2x2x2 mantid's length) from L1 to adult and have never been habituated to the space larger than this don't have any spots, while the mantis placed into the same size container from the larger one gets black spots immediately.

 

[vafan13]

Thanks. Are the glass terrariums larger?I think it is quite small for 6-7cm mantis, especially for slim adult ones (but may do well for larvae, because of their abdonem is turned up). In my opinion, each dimension must be at least 3 mantid's length.

Usually black spots appear just one day after replacing a mantis from large terrarium (or if they live without any terrarium, on potplants) into small one. Mantids who live in small containers (2x2x2 mantid's length) from L1 to adult and have never been habituated to the space larger than this don't have any spots, while the mantis placed into the same size container from the larger one gets black spots immediately.

My wild Chinese developed spots very soon (by the next day) after being put in his plastic container. However my plastic container is quite a bit larger than dokken's at 31 cm x 19 cm x 24 cm high. Quite a bit smaller than being outdoors, though.

Also, when you say you move them from a larger terrarium into a smaller one, is the smaller one glass or plastic? If moving from a large container to a small glass one causes the spots to form, plastic can probably be ruled out. I would almost be surprised if it did. for some reason I find it hard to believe that an insect can get "stressed" enough to cause partial blindness. Which moves me on to another point.

I have to disagree with some of the other posters on whether it affects the mantis. Pre-spots mine walked "normally", however, now he walks quite slowly and is constantly flailing his forelegs in front of him, much like I would walk if I had a blindfold on. He also seems less adept at catching fast moving targets. Both of these observations strongly point towards impaired vision.

 

[Borya]

Also, when you say you move them from a larger terrarium into a smaller one, is the smaller one glass or plastic?

It was plastic. Furthermore, it was matted.

for some reason I find it hard to believe that an insect can get "stressed" enough to cause partial blindness.

Jean Henri Fabre (french entomologist) wrote about ground beetles Scarites sp. fainting after knocking then lightly on a table, and scorpions swooning after being placed into fire circle, of which they can't escape.

I think Arthropods are much sensitive than we think of them.

 

[vafan13]

It was plastic. Furthermore, it was matted.

We need someone that has both small and large glass terrariums to do the same test. If such a move doesn't cause the spots, it's probably the plastic, not the small size.

Jean Henri Fabre (french entomologist) wrote about ground beetles Scarites sp. fainting after knocking then lightly on a table, and scorpions swooning after being placed into fire circle, of which they can't escape. I think Arthropods are much sensitive than we think of them.

Is fainting not simply "playing dead"? Many animals play dead when threatened as a means of defense, as plenty of animals (such as mantids) are generally not interested in dead prey. Or is there something I'm missing. Also, swooning scorpions? By swooning do you mean semi-fainting? Usually when people use the word swoon it is in the same sentence as "giddy school girls" and "rockstar".

 

[The_Asa]

Jean Henri Fabre (french entomologist) wrote about ground beetles Scarites sp. fainting after knocking then lightly on a table, and scorpions swooning after being placed into fire circle, of which they can't escape. I think Arthropods are much sensitive than we think of them.

Ever heard of the oppossum?

 

[Borya]

Is fainting not simply "playing dead"?

Fabre argues that playing dead is not playing at all, not a trick to deceive a predator, but just an involuntary reaction because of fear. Main predators of insects are birds, who (in his experiments) make no difference of picking moving insects or playing dead ones. Scarites (family Carabidae) hunts at night, when there are no insect-eating birds. And, as all carabids, he has acidy liquid for defence.

In your opinion, what kind of aerial predators can be tricked by playing dead? Surely not the wasps - I've seen them hunting even on Sympetrum sp. dragonflies on the rest in the chilly morning.

I thought 'swooning' is synonym of 'fainting'. Thanks for explication.

 

[vafan13]

Fabre argues that playing dead is not playing at all, not a trick to deceive a predator, but just an involuntary reaction because of fear. Main predators of insects are birds, who (in his experiments) make no difference of picking moving insects or playing dead ones. Scarites (family Carabidae) hunts at night, when there are no insect-eating birds. And, as all carabids, he has acidy liquid for defence.In your opinion, what kind of aerial predators can be tricked by playing dead? Surely not the wasps - I've seen them hunting even on Sympetrum sp. dragonflies on the rest in the chilly morning.

"Prey that are unable to fight back against predators (using horns or nasty chemicals, for example) can flee or hide. Insects can fly away or drop to the ground and "play dead." It's not that predators necessarily refuse to eat a dead insect, but that insects lying on the ground and not moving are hard to see."

-from http://blog.lib.umn.edu/denis036/thisweeki...fly_or_die.html concerning the article "Drop or fly? Negative genetic correlation between death-feigning ability and flying ability as alternative anti-predator strategies", by Tatunori Ohno and Takahisa Miyatake, published in Proceedings of the Royal Society B (vol. 274, p. 555-560).

So, say a bird swoops in and pecks at the beetle and knocks it off a rock and into some grass, or whatever. "Playing dead' at this point will make it much harder for the bird to find the beetle than if it moved, even a little. Not saying your/Fabre's argument is wrong, but there certainly is a possible survival-based explanation to "playing dead".

I thought 'swooning' is synonym of 'fainting'. Thanks for explication.

You are right, it is a synonym of fainting. However at least in the US, it is generally reserved for fainting from excitement (such as one might do after winning the lottery) or simply overwhelming joy/emotion towards something. I don't know how it is used outside of the states (I don't think any conversation I've had while in Europe involved the word "swoon"), but in my experience, this is how it is used.

By the way, are you a native Russian or do you just happen to live in Russia?

 

[Borya]

Sorry for long silence.

I think, cathalepsia may be useful in these cases.

1)Quick distancing away from predator. This works when insect is positioned somewhere high above the ground, for instance, on a tree or on high grass. It just need to cuddle it's legs and fall down. Used by those who are not able to run or jump.

2)For predators that don't eat perish. The reason why the predator may do so - because an infection can be lethal for him also. (In human culture, there are some exotic dishes made of rotten meat or fish; but - it is made of healthy animal who was kiiled, not died from disease).

3)If the predator wants only to kill, not to eat. An example not from the world of insects but of mammals: cat being chased by a dog may suddenly drop dead. Dog runs about, barks, and do nothing - it was running to kill, and this result is already done!

But I doubt that 'playing dead' may be useful against birds, ants, wasps, carabids or other specalized predators. They are skilled enough to distinguish living from dead in spite of their motionless or stinking. Maybe it may work against some omnivorous animals that are not too hungry and prefer to find something else rather than sort out what has happened.

I was born in Russia.

 

[kakistos]

I do not think insects faint out of fear. They 'play dead' to escape predators, there is no thought or emotion in that, just instinct. And like people said, a mantis taht does not move is way harder to find than a moving one.

To come back to the original topic:

Some of my Hierodula membranacea subadults also get these spots on their eyes. I think it is because of rubbing their eyes against the container. I keep the containers next to each other and the mantids see each other. They want to castch each other and therefore rub themselves to the container. First I see white spots on the eyes, and when rubbing more I see small black spots. It is exactly at the same level in each eye. I think the turning black is because of an infection.

I have the idea that the mantis can hunt less good when the prey is in front of him. He misses more.

 

[Anleoflippy]

My mantis had that look once but now is gone and does not come back...