Idolomantis diabolica / Giant Devil’s Flower Mantis Care Sheet

One common observation when looking at praying mantis is that they look so “alien”. If that is true then Idolomantis diabolica, the so-called Giant Devil’s Flower Mantis, is the most alien-like of all.

Idolomantis diabolica is a huge praying mantis. Some people suggest it is one of the largest known to science. The adults are bright mottled green, have leaf-like projections on their legs and maintain an impressive threat display.

If you’re looking for the “ultimate” pet praying mantis then you’ve found it in Idolomantis diabolica. While these mantids can be relatively expensive to buy, and are known for being quite difficult to care for in captivity, once you’ve gained some experience with easier mantids like Ghost Mantis and African Mantis then it’s time to upgrade to these beasts!

If you’re considering investing in one of these fascinating invertebrates then read on for my full Idolomantis diabolica care sheet.

Idolomantis diabolica Habitat

The Giant Devil’s Flower Mantis is a widespread mantis found across much of Africa. It is known to occur in Ethiopia, Kenya, Somalia, Tanzania and Uganda. In other words, this is a mantis that is used to high temperatures; something which is key to their successful care in captivity.

Originally described by Saussure as long ago as 1869, female Idolomantis diabolica can grow up to 13cm long (5”), while males attain a slightly smaller 10cm (4”). In the wild these impressive predators will feed on anything that they can subdue.

When keeping such a large species of praying mantis you’ll therefore need to ensure you have a decent-sized cage for your pet, with a constant supply of live insects to fuel their growth.

Cages for Idolomantis diabolica

Cage sizing is of crucial importance for all praying mantis. Praying mantis moult by attaching their legs to a fixed object and then “sliding” out of their old skin. This means that suitable vertical height is crucial.

Generally speaking hobbyists recommend a cage that is 2-3 times as tall as your mantis is long. This is a rule that has worked very well for me over the years. For large Idolomantis diabolica this means a cage of some 30-45cm in height.

Width is less of a concern, but should be at least twice as wide as your mantis is long. Roughly speaking, therefore, a large juvenile or adult mantis will appreciate a cage of around 20-30cm in width and some 30-45cm in height. Please note these are minimums, so if you can provide a larger cage then all the better.

It is worth re-iterating that these are large, impressive, alien-like insects, so they can look fantastic in a naturalistic tank setup.

One factor worth bearing in mind is that Idolomantis diabolica can have difficulties climbing on very smooth surfaces. This should be taken into consideration when selecting a tank, to ensure they are able to clamber about effectively.

For Large Juveniles and Adults

There are three common types of cages that can work well for Devil’s Flower Mantids. These are:

Exo Terras & ReptiZoo Terrariums

If you want to create an amazing display where you can really enjoy watching your pet then Exo Terra’s and ReptiZoos can represent a great option. I use these for many of my invertebrates including tarantulas and mantids. My larger Idolomantis diabolica happily inhabit the 30cm x 45cm model.

Pros:

• Very attractive display
• Easy to feed & clean thanks to front-opening doors
• Easy to heat
• Light canopy available for the top
• Mesh lid means great ventilation
• Textured background can make climbing easier

Cons:

• Can be expensive
• Will need to consider the addition of twigs and branches for climbing
• Relatively heavy and fragile

Mesh Cages

Mesh cages are very popular among Idolomantis diabolica keepers because the mesh is so easy for these mantids to climb on.

Pros:

• Cheap to buy
• Excellent ventilation
• Allows easy climbing
• Quick and easy to clean
• Lightweight

Cons:

• Difficult to heat in winter
• Harder to find than other cages
• Doesn’t look attractive

Plastic Storage Boxes

Exotic pet owners are masters of “repurposing” containers intended for other purposes. There are now more plastic storage boxes available than ever before. While many are “opaque” so may not offer the very best view of your mantis they’re easily sourced, cheap to buy, and with a little DIY can become a suitable home for your mantis.

Pros:

• Widely available
• Come in a range of different sizes and shapes
• Reasonably cheap
• Lightweight
• Stackable

Cons:

• Not the best-looking for display purposes
• Require the addition of ventilation
• Lids don’t always close properly

None of these cages are necessary “better” than others, with each having their strengths and weaknesses. With the right knowledge any of these can become a practical cage for your Idolomantis diabolica.

For Hatchlings & Small Juveniles

A range of different containers can be used to house smaller Idolomantis diabolica. Here are some popular options:

Deli Cups

Deli cups are a cheap option popular with mantis keepers. These can be sourced either made from plastic or polystyrene. The polystyrene option is better, as the material is easier for your mantis to grip. Be sure to add ventilation to the top, either by puncturing holes in the lid or, even better, throw away the lid entirely and use a small piece of muslin or net curtain held on with an elastic band.

Cricket Tubs

If you’re like me then you’ll receive a constant supply of clear plastic cricket tubs. For tiny mantis these can make suitable cages. I stand them on end and line the inside with a few layers of kitchen paper. In this way the cage not only has suitable vertical height, but the paper towel allows the young mantis to grip easily.

Plastic Storage Boxes

In for adults, plastic storage boxes can make suitable cages, if you ensure that your mantis can climb the sides OK. For example, plastic sweet jars can be used, so long as twigs and branches are includes to aid with moulting.

A Note on Communal Rearing

Most praying mantis species are not only carnivorous – they’re also cannibalistic. This means that they will slowly feed on each other if kept together. While there are some species that are considered at least semi-communal (such as the Ghost Mantis) experts cannot agree on the Devil’s Flower Mantis. Some keepers claim to have successfully reared this species communally, while others report eye-watering losses.

Personally, with such an expensive mantis, I haven’t yet dared try my luck.

That said, if you do decide to try and rear Idolomantis diabolica as a group then please appreciate that you’ll need to provide a much larger cage.

Tank Decor

While it is possible to keep Idolomantis diabolica in an attractive, naturalistic set-up (as I do for some of my adults) in all fairness this isn’t really suitable for smaller mantis.

The easiest set-up is really quite minimalist. Either use no substrate at all, or line the base of the cage with kitchen paper. Include some suitable perches such as twigs, branches and pieces of cork bark and your Idolomantis diabolica should be perfectly happy. Even better, routine feeding and cleaning becomes super simple.

I keep numerous spare tubs for my babies, so I can simply open up a tub, move the mantis gently into another identical tub I have set up. I then remove the kitchen paper from the old cage, give it a quick wipe around, and then move the next mantis into this freshly-cleaned cage. This maintains hygiene with the minimum of effort.

Heating & Temperature

Coming from Africa, the Devil’s Flower Mantis needs a warm environment to thrive. Many experts claim that they require a temperature of up to 30’C in captivity, though I find that my specimens do well at a temperature of 24-26’C.

The key message here is that your Idolomantis diabolica is almost certainly going to require some supplementary heating.

Heating large juveniles and adults is reasonably simple. Unless you’re lucky enough to have an animal room that is constantly heated then a low power heat pad or heating cable can be a great way to keep your mantis warm. These are quite safe to leave on 24/7 and cost very little to run.

The flipside is that these low cost heaters don’t get particularly warm. They may be suitable for tarantulas, and they may even work well if you’re housing your Idolomantis diabolica in an Exo Terra. However if you’ve opted for a mesh cage, or you live in a very cold area, then you may require a heater with rather more power.

There are a number of options here. For example, some mantis keepers use a heat lamp – combining both warmth and light. Others opt to use ceramic heaters, which will get much hotter but don’t produce any visible light.

Whichever option you select, there are two important considerations…

Heat Only Part of the Cage

Your mantis should be able to move to warmer or cooler areas as suits them. If you’re planning to heat your Idolomantis diabolica cage to the high twenties then your pet must be able to escape from the worst of this warmth on occasion. Aim to heat one part of the cage, while leaving the other area unheated to provide this temperature gradient.

Always Use a Thermostat

Exotic pet heaters can get very hot indeed; especially ceramic bulbs. To prevent any chance of overheating you are strongly advised to combine your mantis heater with a thermostat. You can learn more about choosing a thermostat in my guide here.

Lighting

Like other mantis, Idolomantis diabolica is diurnal, meaning that it is awake during the day. They have excellent eyesight, which they use to zero in on their prey.

This means that your mantis will need sufficient light to behave naturally and successfully catch their prey.

It can be advisable to keep your mantis is a light, airy room which benefits from plenty of natural sunlight. If you do this, however, be sure that no direct sunlight reaches your mantis cage, or overheating can occur.

As an alternative one can provide artificial lighting. My larger mantids are housed in Exo Terras, where the stand-alone lighting canopy makes adding a light simplicity itself. Younger mantis are kept en masse in separate containers, all housed within an artificially-lit vivarium.

Water & Humidity

Great disagreement exists regarding the “correct” humidity level for Idolomantis diabolica. Some keepers claim they need a high humidity at all times, while others claim that juveniles are best kept much drier.

Personally I have taken to keeping my specimens in reasonably dry cages, but lightly misting the tank twice a week with a houseplant mister, so that my mantids can drink from these droplets if they so choose.

So far, this system seems to be working well.

I do not provide an open waterbowl, for fear of my mantids accidentally drowning.

What Does the Devil’s Flower Mantis Eat?

The Devil’s Flower Mantis is carnivorous and will eat any prey that it can successfully subdue.

As pets, this generally means feeding Idolomantis diabolica on live insects.

Many experts report that Idolomantis diabolica will only eat flying prey – fruit flies (Drosophila) as hatchlings, and larger flies as adults. It is easy to purchase these as non-bleached maggots, which will soon hatch into adult flies.

All the same, my personal experience so far is that Idolomantis diabolica won’t only feed on flying prey. To date I have managed to rear numerous specimens to adulthood on a diet of crickets and locusts of varying sizes.

Like many other pet invertebrates, the Devil’s Flower Mantis will typically go off their food for a week or two when they are preparing to moult. Otherwise I feed my Idolomantis diabolica on a daily basis.

Handling the Devil’s Flower Mantis

Idolomantis diabolica is both large and easily-stressed. Indeed, some mantis enthusiasts have suggested that regular handling of Idolomantis diabolica may actually shorten their lifespan. Others routinely handle their mantis – apparently without issue.

The so-called “deimatic display” than Idolomantis diabolica shows to scare off potential predators is thoroughly impressive, but you shouldn’t deliberately try to trigger it by scaring your mantis.

So we have here a species that, as an adult, can fly, has large spiked front legs and that may suffer from stress. Consequently while it is possible to handle this mantis, in my opinion it is better to consider this a “display” species for your collection.

If you do need to want to handle your mantis then let it walk onto your hand, nudging it gently from behind to coax it along if necessary. Never “grab” at the mantis or you may elicit a negative response. Lastly be sure to keep windows and doors closed lest your Idolomantis diabolica tries to fly to freedom.