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Illness, Infection, & Injury In Praying Mantis

Fungal infections, bacterial infections, eye rub, mismoults, old age, physical injury and more, our in-depth guide to praying mantis healthcare cracks down on illness in praying mantis.

Table of Contents

Fungal Infections

Fungal infections occur most often in moist, warm environments where stale air is allowed to build up.

This makes low ventilation enclosures the perfect fungal breeding ground. In our content, we hammer down the importance of having great ventilation in enclosures, as it is crucial for preventing deadly health issues. To learn more about ventilation and how to house your mantis, check out our article below on enclosures.

Read: The Complete Guide To Housing A Praying Mantis And Creating Enclosures

Fungal Infections have numerous ways to bring down insects. This cicada infecting fungus, Massopora, eats into the lower abdomen of the infected insect, encouraging mating to further spread the infection to others. 

The infection of Ophiocordyceps unilateralis in ants controls the brains of ants as they walk to a prime location for the fungus to grow. The ant then dies, and the fungus sprouts from its body to further spread its spores.

Fortunately, mantids are not prone to such violent infections. Regardless, fungal infections are still deadly, and, in mantis, work to eat through the exoskeleton in this same fundamental way.

Fungal infections in a mantis display as either green or pale blotches on the surface of the skin. A late-stage infection will show visible decay by the fungus into the animal’s exoskeleton; the mould has created a wound.

1. Preventing Fungal Infections

The most important way to prevent fungal infections in your mantis is to promote airflow into the enclosure via sufficient ventilation. With airflow, stale air and mould spores can not build up. 

Second to this is the regulation of moisture. In a wet, stuffy enclosure, water evaporates less. A constantly wet enclosure will inevitably promote mould growth. Remember that an enclosure with less ventilation, for example, a glass vivarium, will be much better at holding humidity than, say, a mesh enclosure. You should account for this accordingly when choosing an enclosure.

So, how do we keep mantids that require extremely high humidity without growing mould? Bioactive Enclosures.

Bioactive enclosures are naturalistic enclosures designed to replicate the enclosed animals native environment. 

Bioactive enclosures are decorated with live plants, soil substrate, but most importantly microfaunae. Microfaunae like springtails and isopods feed on mould, dead feeder insects, and plant matter. For this reason they are invaluable to the health of many exotic & tropical mantis species, where you’ll see bioactive setups used most often.

2. Curing Fungal Infections

The “science” of mantis care is very limited, so we can only offer advice based on what little information exists along with our own experience.

UV light naturally antifungal & antibacterial, and we have had success in exposing our infected mantids to wide spectrum UV light for several hours each day until the infection cleared. With this in mind, using UV bulbs in a setup, as you would with a reptile, should help to somewhat prevent mould and bacteria from initially growing. If you have a setup that frequently battles with mould, go bioactive and use a UV light.

After finding an ill mantis or fungus, you should thoroughly sterilise your enclosure, using dry substrate to keep the humidity low as your species can tolerate while it fights the infection.

As with most health issues, it’s important to catch problems earlier rather than later. Mould decay on the outside of the body is substantially easier to cure than internal mould issues from inhaling or consuming spores. 

Bacterial Infections

While we don’t know much about how mantis deal with bacterial infections, we know a little about how they work in general.

Bacterial infections kill due to harmful bacteria being consumed by the host, or somehow entering the body. The bacteria then enters the hemolymph (bug blood) and causes sepsis. A prevalent form of infection in praying mantis and other insects is caused by bacteria from the genus Wolbachia.

While we might not know much about bacterial infections in mantis, we do know how these infections display in other insects. Some common symptoms of bacterial infection in insects include dark spots on the body, general dark discolouration, a sudden disinterest in food, less activity, paralysis, vomiting, and diarrhoea. It’s also noted that insects that have died from bacterial infections quickly turn brown and floppy after death.

A picture of different bacterial infections in insects. While many infections display differently, mantis forums often post about dark patches on the exoskeleton & dark discolouration. Therefore, this should be the most important symptom to look for in praying mantis

1. Curing Bacterial Infections

If you suspect your mantis has a bacterial infection, you should clean & sterilize your enclosure, purchase new, healthy feeders and keep your animal as fed & hydrated as they will accept while their immune system tries to fight the infection. Keep them in a well ventilated environment or simply free range them as they recover.

2. Preventing Bacterial Infections

Just like fungal infections, ventilation and a clean environment is the key to a healthy mantis.

Preventing bacterial infections also boils down to the health of your feeders & their environment. It’s important to give your feeders good living conditions and ensure they are healthy for the sake of your pet. Do not feed your mantis any insects that appear ill. 

Abdominal Wounds & Punctures

Abdominal wounds are a risk predominantly to mature mantis, especially females. Female mantis are gluttons and internally develop masses of eggs as they prepare to lay ootheca. Punctures can occur during mating, from males puncturing females, from falls or from curious pets. Small punctures can be easily treated, with resulting infections being the greatest concern. Mantis with large wounds should be promptly euthanised 

1. Preventing Abdominal Wounds

Avoid adding sharp/hard objects into the enclosure, for example, spikey sticks, crystals & rocks. This will prevent the mantis from falling onto sharp objects and injuring themselves.

Avoid overfeeding as the increased pressure inside of the abdomen increases the risk. For adult female mantis, the majority of space in the abdomen will be taken up by eggs.

2. Healing Abdominal Wounds

Abdominal wounds in mantis should be sealed as soon as possible with cornstarch, flour, or other clean substitutes via topical application with a soft brush or cotton bud. This will create a seal around the wound, preventing hemolymph loss and aids coagulation so the wound can be efficiently sealed.

For several days after, you should closely monitor your mantis to ensure the wound has not reopened or become infected. Apply additional cornstarch when necessary, say, if the wound reopens. Keep your mantis hydrated with fluids as they may be dehydrated from loss of liquids.

Over time, cornstarch will crumble off or can be wet and removed after the wound has entirely healed if necessary.

Limb Loss

There are two major types of limb loss in praying mantis: limb loss through mismolts & general injury and limb loss through old age & natural degeneration.

1. Limb Loss Through Mismolting & Injury

It’s not uncommon for a mantis to lose a limb after a moult. The legs of insects have several points which they can harmlessly detach from the body. These are called “break off points”, and muscles in the break off point constrict to prevent blood loss. This is why you should not amputate a limb yourself, and allow the mantis to do it naturally.

 Losing a leg is not normally fatal, and limbs will be fully regenerated over the next couple of moults.

Losing the raptorial front arms, however, is a significant problem. If your mantis cannot hunt, it can’t eat. In this case, you should hand feed your mantis.

Read: The Complete Guide To Feeding A Praying Mantis

If a limb has been lost after reaching adulthood, they will not be regenerated. It is up to you as the owner to discern the quality of life your pet has with missing limbs. Complications arise if your mantis has lost multiple legs, and a moult is approaching. Before detaching from its exoskeleton to moult, a mantis must ensure it is firmly gripping onto a surface. If many legs are missing, the chance of falling mid-moult increases for every leg lost.

Old Age

1. Age Related Limb Loss

Although all insects & arachnids molt to grow bigger, certain arthropods, generally those that live longer, molt to renew & strengthen their exoskeleton. Mantis, however, do not molt again after adulthood.

This means that over time, parts of a mantises body, especially those as delicate as the legs, become damaged. Close to old age, it’s not uncommon to see the tips of legs or parts of limbs fall off. This may be more common in male mantis & small mantis with thinner body parts.

There are some signs of limb loss to look out for.

First, a limb will seize up, unable to move normally. The mantis will then stop using it to get around. 

For example, if the raptorial tibia seize up or break, your mantis may instead use its raptorial “claws” to move around.

This change places unnecessary stress on parts of the body not meant for moving. It’s possible that mantis can feel discomfort from this, as often they will intentionally amputate their own limb. The overuse of a body part can cause it to break off naturally.

This seems to be just a natural consequence of wear and tear on the exoskeleton. The best way to combat this is for you to keep your mantis in a spot that it is comfortable in and unlikely to move around. Avoid roughly handling your pet.

2. Weakened Immune System

The immune system in elderly mantis weakens and signs of bacterial infections appear. While its not certain, this age-related natural degeneration of the immune system happens to the majority of other animals. It’s purely observational, but this presumably happens in mantids as well.

While this is more of an incurable symptom of age, you may be able to influence it by ensuring your mantises enclosure and surroundings are consistently clean. Feeders should be kept in a hygienic environment, thus limiting the bacterial load consumed when your mantis eats, just as advised in our section on bacterial infection.


Mismolts refer to the deformed state of a mantis after a moult. Often mismoults are the result of improper care, such as humidity levels that are too low. Despite this, mismoults can happen through pure fluke. Science suggests that molting issues may be responsible for up to 90% of deaths in arthropods, so it’s an incredibly common health issue in the hobby.

A mismolt in an adult Chinese mantis. You can see deformed, bent legs and crumpled wings. This mantis is an adult so he will not molt again, and live the rest of his life with these deformities.

Mismolts are easily avoidable and simple to understand, so we make sure to always mention molting in our care guides.

Preventing mismolts is as simple as keeping your mantis hydrated, using a mesh-topped enclosure, and ensuring the RH (relative humidity) in the correct range for your species. It’s really this simple. We cover this topic in greater detail in our complete guide to molting. 

Read: The Complete Guide To Praying Mantis Molting

2. How To Deal With Mismolts

Mismoults are usually difficult for your mantis to recover from. Mismolts can be mild, with only damaged wings or legs. In severe cases, the thorax can curve, preventing the digestion of food. Mandible parts may be missing or damaged, preventing your mantis from chewing food. Mantis can lose legs, and the front raptorial grabbing arms can become deformed. A mantis that has mismoulted on the final moult is extremely difficult to help as they can’t molt again to correct any physical bodily issues.

Euthanasia is often a humane choice when dealing with mismolted praying mantis. It’s up to you to assess their condition and quality of life. When in doubt, online mantis forums are more than happy to offer advice.

Eye Rub

Eye rub is the degradation of a mantises eyes due to friction resulting in black spots, blindness, or infection. Eye rub is caused by visual stimulation from outside of the housing setup, prompting the mantis to rub its eyes up and down the enclosure walls in an attempt to reach it.

An image of eye rub in a mantis, the uneven black marks on the top of the eyes. The dark spots below are her pseudopupils, a natural optical effect that is seen from any angle to give the illusion of always being watched. 

If your mantis is not yet an adult, it’s possible for them to molt out of eyerub. Just as with any injury, it may take several molts for damaged parts to return to perfect condition. Eye rub cannot be healed beyond adulthood, so prevention is key.

Preventing eye-rub is as simple as removing any other insects or prey items from your mantises view, or by covering view of them.

12 Responses

  1. Help! Our giant African praying mantis keeps puking really dark liquid smells like vinegar. He’s pooping amd eating still. It started after feeding a newly hatched housefly. We i’ve been good loading fruit flies with Minooka honey and feeding mantis diluted honey from local hives for 3 days but woke up this morning with more puke.

    1. Hello there,

      Sorry to hear that your giant African mantis is not doing well. The black puke that you’re describing happens on occasion in mantis and usually isn’t usually something to worry about. That said, it’s usually a sign of digestive issues, and I wonder if it’s due to your frequent feeding of honey to your pet. It’s not recommended to feed large amounts of thick honey to mantis as it can gum up their digestive system and cause digestive blockages. If you do decide to feed your mantis honey, you should dilute it to make it thinner. Overall, honey and plant-based foods such as pollen are suitable as a treat or supplement, but should not make up the bulk of your pet’s diet. Mantis and most other insectivorous invertebrates thrive on a high-protein diet from high protein feeders such as dubia roaches, morioworms, locusts, and crickets. Hopefully this helps! If you have any further questions, feel free to email me at [email protected].

      Best of luck!

    1. Hi Linsey,

      We definitely don’t recommend flushing. In theory, the ideal method of euthanasia would be via crushing, however this can be easily botched especially with larger animals. Currently, the recommended method of euthanasia for pet invertebrates is freezing. Hope this helps. 🙂

  2. Hello,
    My Deadleaf mantis seems to be weakened, it can get hold of anything and keeps falling.
    It has also lost one of the front legs which is attached to its claw, claw is fine but its missing the leg part.
    Mantis eats well no problem when I hand feed but I think it has lost the ability to hunt since its just so clumsy.
    Only new things I have done to its enclosure is I have made it bio active and also added some isopods. I have been spraying water to enclosure and added some new plants.
    please help me to do something.

    1. It sounds like your mantis may be getting old? This is usually why they lose the tarsus on their legs. Adding some mesh or coco matting to sides of the enclosure may make it easier for it to climb around. Hope this helps.

  3. An injured mantis appeared on my balcony and I am trying to take care of it. All legs in tact, wings look nice, and he let’s me touch him to examine. The one thing I notice looks off is the underside of his abdomen. It looks like it’s twisted. I tried to gently move it and it “latched” onto me like sticky feet. Do you know what’s wrong/how can I help the little dude?

    1. It’s hard to say what is wrong without seeing the mantis. It could have been caught by a curious cat or hit by a car or just getting old. You could offer it some water or diluted honey on a q tip. If you don’t mind handling bugs, perhaps pre-kill something to feed it. You will need to cut the head off the bug and offer the soggy end of the body to the mantis mandibles. If it is interested then it will start nibbling and hopefully take the bug from you. If it isn’t eating or drinking then there is probably little hope i’m afraid.

  4. So my mantis has black rotting skin on the side of its abdomen. This has appeared out of nowhere and he also moving slow and sluggish. It’s grip isn’t quite there and one of its antennas isn’t moving. It’s only half way through its life. I’m not sure what’s wrong with it?

    1. Hi Kevin, it doesn’t sound good. It is probably a bacterial infection. Perhaps it injured it’s self which would allow bacteria to enter the body. The best course of action would be euthanasia.

  5. I have a new mantis friend, they often find me which is nice. This one can’t extend its forearm? It was twisted and caught up in the rest of its arm and I think it’s spike is going into the elbow. Straight away she let me hold her, and even use a utencil to open her legs up without hesitation. But they keep closing. Even after I try stretch them. She can walk, but not as normal. Her belly is fat so I’m guessing she can still get a feed. I tried putting her in an enclosure but she didn’t seem comfortable and when I tried to rearrange a few things, she just reached out with her closed shut arms and climbed back onto my hand.
    Can i help her use her legs arms again, and if not, should I take care of her so she doesn’t started maybe or get eaten??

    1. Poor thing, I’m not sure what has happened to her but it’s great that you are caring for her. If she doesn’t like being in an enclosure, perhaps let her live on a house plant. I have had many free range mantis and they generally do well and don’t make a nuisance of themselves. So long as the plant allows plenty of grip she should be fine. You might have to assist with feeding though as she won’t be able to catch or hold prey easily. Reply to this comment if you need advice on that.

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