How does the Instar rank work?

So with the Instar "rank" of each mantid does it depend on what species it is for how many time it will moult? How do I know when mine has reached sub-adult to adult? I know very obvious signs like the wings and such but how will I know when they are full grown?

it does depend on what species. for example with idolomantis, males moult 8 times, females moult 9 times (before adulthood). with gongylus, males moult 6 times before adulthood, females 7. i think most species is around this mark (6/7 moults to adulthood) though i tend to lose count. you will know when a mantis is adult when it gets wings (for the most part. some species have incomplete/"bud" wings, and there are some species where the female has no visible wings, like oxypilus). it will not moult anymore once it has wings/is adult.

How long do they tend to live once they reach adult?

it's too hard to say as it is so variable, depending on things like how much/often you feed them, what temperature you keep them at, what species they are, and their gender. really any figure i give you, you can probably find someone to say "i had a female that lived for twice that long!" for example, while somebody else may have had one that lived for half that! in general males live alot less than females as adults. alot of females can live for around 5 or 6 months, males 3 or 4 but like i said you may get some that live alot more or alot less, it just depends on so many things.

Thank You your help is greatly appreciated. It gives me a better idea of whats going on with my mantids.

Do you know if a sickness can claim a mantis within hours? I have four in a 10 gallon tank and 2 of them are in their 4th going on 5th instar and 2 in their 3rd going on 4th and one of my smaller ones died within the last few hours. the other 3 don't appear to have moved from where they are but my 4th is dead with no apparent wounds of any kind. I put him under a magnifying lens and can't see any physical reasons why it would have died. any ideas?

what species are they? (i have never kept them but i have read alot about how) chinese mantids (Tenodera) and european mantids (M.religiosa) tend to die alot "for no reason". i can't vouch for this as i have never kept either species, but if you do a search for them you will probably find some threads about it. i dont know if a sickness can claim a mantis within hours, as it is almost impossible for us to tell what is going inside the mantis, or when it starts to become sick. i would imagine alot of problems develop quite unknown to us. so many times you see people say "they look fine" or "they seem happy" only to have that same "happy" mantis die within days. while sometimes it can be outwardly obvious a mantis is on its way out (some kind of serious injury for example), alot of the time the problems are almost impossible to spot from the outside and manifest themselves at a biological(? not sure that's the right word...) level.

but i have read alot of people saying their mantis just dies without any wounds or apparent physical reasons. i would say it has to point to SOMETHING being wrong with how you are keeping them. quite what that is is anyone's guess, there are way too many things that could go wrong. too hot, too cold? too humid, too dry? not enough ventilation? infections, mould? hunger? etc etc. it would be almost impossible for me to say why it may have died without knowing more about the conditions it is kept under, and even then i think it would still be very difficult. partly because i am absolutely NO expert on mantis care, and partly because we can't really conduct post mortems on them like we can with humans. which can be a shame sometimes if you swear blind you are offering the right conditions and the mantids still die, you can't exactly learn from your mistakes and change the conditions. some things you can try to learn from, things like trouble moulting can point to humidity/space/surfaces etc, but sometimes when the problem is less obvious i guess we are left blind to our mistakes

EDIT: i realise i just took two whole paragraphs to say what could have been said in two sentences, but anyway <_<

One bad cricket can infect and kill a mantis in less than an hour

My other mantids seem "fine" but I'll have to see how they do. I have an ooth that I'm expecting to hatch soon and I am setting up 2 more enclosures in different ways to see how they do. I'm in an experimental stage right now with mantids. I just started keeping them so to have 3 out of 5 still alive I think is pretty good. The first one fell victim to a bad molt then cannabalism so I don't put that on their environment. Thanks for the info it helps put things in perspective.

Birdfly: what do you mean by a bad cricket? sick, infected?

Well its a long story but it seems crickets can lead to premature mantid death, they can carry some form of bacteria that when injested by a mantis can kill it very quickly, some mantid species are more suseptable to it than others but i have lost some of the less suseptable mantids species in very similar fashon so i just dont use them for my mantids any more only spiders and lizards.

I prefer to stick with what imo mantids would normally encounter like flies, roaches, beetles and there larvae, lepidoptera and there larvae, locusts etc and wild caught insects like bees, wasps, true bugs, grasshoppers, hover/drone flies etc

Please try searching the forum for the answers.

Can you identify what instar a mantis is by measuring how big it is? I have a Tropidomantis and it's 1.5cm - 2 cm. Can you please help me identify what instar my mantis is?

I can guesstimate if I kept the species before. Otherwise, I can only kinda tell if it's adult or subadult (or subsubadult.).