Let's say that in a fictional world (the world of Heroes of Might and Magic IV in my case) the square-cubic problem of insect respiration is somehow solved, so I have giant mantes roaming the area, and used in enemy ranks (let's say, they are controlled by magic). It is hard to judge the exact size (as miniatures on the battlefield are not as different from each other as some art shows), but the mantes are at least as large as a horse a typical humanoid could ride, and could be as big as the mighty Black Dragon in this HoMM III intro.

I ask this question because I remember trying to kill or otherwise harm insects in my childhood, and they were by no means really fragile! Yes, if you throw it into a fire, it will burn, but I can't imagine any other way to kill a mantis except from evoking a fire big and hot enough. Chitin is very resistant to being cut, smashed, etc. Moreover, insects are dumb, and as far as I know, they don't feel pain at all, so even if it loses a limb, it is not stopped.

Is there any way to quickly dispatch a giant mantis without resorting to fire?

  • $\begingroup$ I wonder...if you scale up a mantis to the size you're describing, how heavy would it be? Would it become susceptible to becoming mired in mud? It may be too much to expect it to be killed that way, but it could be effectively removed from the battle. $\endgroup$ Commented Apr 29, 2017 at 23:52
  • $\begingroup$ Shoot it in the brain? $\endgroup$
    – Kilisi
    Commented Apr 29, 2017 at 23:54
  • $\begingroup$ Crush it with stone boulders. Pierce it with javelins thrown by a catapult. Make it fall into a pit with vertical stakes at the bottom. Sick a domesticated giant scorpion on it. Transform it into stone with a magic spell. $\endgroup$
    – AlexP
    Commented Apr 29, 2017 at 23:59
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    $\begingroup$ I think you need to define how resilient the chitinous shell is. Give us densities (or use the standard) and how thick it is. My first thought is crossbows, but if that's not enough you probably want a ballista. $\endgroup$
    – James
    Commented Apr 30, 2017 at 0:02
  • $\begingroup$ Do you want this mantis killed strictly with scientific means? If you are fighting with units based on HMM, then there are a lot of options. Can you get a Titan/Behemoth on your side to squish them? Can you armor up some Crusaders with defensive spells tough enough that the mantis can't cut through there armor? What about the Haven factions catapults and ballista? You need to define how much Heroes of Might and Magic you want in the answer. $\endgroup$
    – kingledion
    Commented Apr 30, 2017 at 1:48

7 Answers 7



With a chance to prepare

Use traps. A horse-sized or larger creature would be badly damaged if not killed by falling in a pitfall. As AlexP's comment above suggests, a large rock could then be used to crush it. Similarly, if the giant mantises are attacking a castle/fortress with high walls or towers, heavy objects could be thrown from the top of the walls/towers.

Feed it poisoned meat.

In a fight

Target the weak/unarmored points. When plate armor was common, techniques were developed to fight men in armor - such as 'half-sword' techniques, knocking them down/wrestling them and using daggers through the joints, etc. The joints of a giant mantis would be unarmored, as would the (very large) eyes. Destroying the eyes wouldn't kill it outright, but would definitely make it much less effective in a fight.

Now, this would be complicated because insects' anatomy makes a quickly-mortal wound harder without really massive trauma (such as a human squishing a normal-sized insect). So cutting off the head wouldn't keep it from flailing around and slashing up people with its claws. But enough people should be able to manage it without fire, though losses might be heavy.

Blunt trauma. In addition, a large enough impact could kill by smashing the insides by force transmitted through the exoskeleton - and they'd probably be relatively vulnerable to this sort of thing, there wouldn't be the padding between armor and flesh that humans wearing metal armor used.

  • $\begingroup$ As a modification to "blunt trauma": Not-so-blunt trauma. Just look at IRL warhammers, en.wikipedia.org/wiki/War_hammer They were made almost exactly for large, armored insects: Hard outer shell but squishy organs beneath the topmost layer. All the advantages of a club but even better $\endgroup$
    – Hobbamok
    Commented Apr 7, 2023 at 14:06

Make (or find) some (a lot) of ruby dust

Or other hard crystal. Glass might work, I just know ruby dust is actually used industrially as it's effectively a permanent solution to a cockroach problem (the ruby dust never goes away, it lingers and lingers). Boric Acid would also work.

Every grain has ridiculously sharp edges, is super tiny, sticks to literally anything, and is ultra durable. Sand-sized is probably sufficient for the scale we're working with.

Dump a load of it on the mantis (and then run, hide, and wait).

Eventually the hard edges will get into the giant insect's joints and cause tiny abrasions and cuts and it will dehydrate the insect through lost body fluids. Literal death from a thousand cuts.

Its not going to be a fast way to kill these monstrosities, but it's a very passive solution that doesn't involve deadly toxins that might harm people, plants, or other animals. Still wouldn't want to breath any of it while you're in the process of applying it, but once it settles it's safe.

  • 1
    $\begingroup$ Boric acid and diatomaceos earth sack bombs would work as well, but could be launched from catapults. $\endgroup$
    – Paul TIKI
    Commented Apr 30, 2017 at 6:45
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    $\begingroup$ Could be a good solution to destroy a nest of them, so you have my upvote, but not a battlefield solution, so I will not be able to accept it. $\endgroup$ Commented Apr 30, 2017 at 13:59
  • 1
    $\begingroup$ @Baskakov_Dmitriy No worries about the accept, sometimes my answers just approach problems from a different direction. Like a question that asked if it was possible to build a bridge to the stars, most answers talked about the material constraints, I talked about construction time. <Salute> $\endgroup$ Commented Apr 30, 2017 at 14:51

Chemical warfare.

There are chemicals that are extremely toxic to insects, but far less toxic to mammals. Take DDT, for example, if a human eats a spoonful of it, they are going to live (if humans are as susceptible as rats, the LD50 is about 50g); and DDT is almost non-toxic if applied to human skin. But it will kill many insects at extremely small doses (LD50 of a few μg). And DDT is old tech, there are newer insecticides which kill at even lower doses. If your mages can whip up a batch of DDT, the insects don't have much chance.

If your tech level doesn't allow for organophosphate insecticides, you can hope to create some of your own from plants that are naturally insect resistant. Chilli, Hemlock trees and other plants have insect-killing properties. While not nearly as effective as synthetic insecticides, they could deter, weaken or even kill mantids.

DDT kills in seconds for real insects. Organophosphates are cruel chemicals that cause massive damage to the sodium ion channels in nerve cells, causing them to fire randomly. The insect spasms repeatedly and dies as the nervous system completely fails. DDT is related to nerve gas like Sarin. Natural insecticide like the Eastern Hemlock would be much slower.

  • $\begingroup$ How fast do the insecticides kill? They could theoretically be created by magic. $\endgroup$ Commented Apr 30, 2017 at 14:03
  • $\begingroup$ I'll vouch that modern flying insect spray will take down a dauber wasp in literally 3-4 seconds. I'd have to look at a can to say what's in it, but I guarantee it's an organophosphate of some sort. $\endgroup$
    – Zeiss Ikon
    Commented Apr 16, 2020 at 18:20

A directed fire weapon (hose, sprayer or bomb-thrower) using Nicotine solution (or dust) from tobacco. Up until the invention of DDT, Nicotine derived from tobacco was used commercially as a crop insecticide. Either ethanol or various oils may be used to extract the Nicotine, which may be up to 7 -- 8 percent by weight in some varieties. (e.g. Burley.)

It won't kill unless it gets absorbed, so a face shot is your best bet, and the head/thorax or thorax/abdomen joints as secondary targets. Proximal (nearest the body) leg joints as a last-ditch target.


"Full text of "Insecticidal uses of nicotine and tobacco: a condensed summary of the literature, 1690-1934"


which tells us that:


A little casual information on the physiological effect of nicotine is to be found in numerous papers from 1895 to 1934, but only a few studies were originally planned to determine how nicotine kills insects. A few. other papers give additional information which is probably correct but not supported by experiments. It was the fundamental information on this point that led to the preparation and use of nicotine dust.

The symptoms of nicotine poisoning in the experiments with bees in 1916 were, divided into three stages. First, bees that had eaten nicotine soon became abnormal in behavior, and the legs and wings were partly paralyzed. Second, the paralysis progressed from partial. to complete, the hind legs and hind wings usually being the first to be completely paralyzed, then followed the middle legs and front wings, and, finally the front legs. Third, the bees wore apparently dead except for slight movements of the head appen- dages, legs, and abdomen. Regardless of how nicotine is applied, it seems to kill by motor paralysis; that is, it first affects the nerve centers that control muscular movement.

Credit to James K.: Tobacco is in the Nightshade family, as are tomatoes, eggplant, potatoes, and chillies. But tobacco has orders of magnitude more Alkaloid per unit mass of dried plant matter than the ones we eat.


Give it some coffee

No, seriously. Caffeine for some reason has a real adverse effect on insect and other invertebrates, and is often downright lethal to them. This best known in spiders, but also occurs in mosquitoes, butterflies, mealworms, milkweed bugs, snails, slugs, and more. There are some insects that are immune to caffeine (some species of beetles are, but in some of these cases they still show evidence of being negatively effected physiologically), but the vast majority are not. To the point that some research is looking into caffeine as an insecticide that won't be toxic to humans.


You put an arrow or bolt into each eye, and take out any other relevant sensory organs the same way, than dismantle it from safe range with poleaxes, limb by limb.

It's not especially clever, and it takes several warriors, but it's brutally effective.


Just give them a little push

You say that

(...) the square-cubic problem of insect respiration is somehow solved (...)

But that is not the only problem with scaling a mantis. A giant mantis probably wouldn't be able to walk, and here is why:

Would a humanoid insect species even lift?

Such mantises would either move veeeeeeeeeery slowly, slower than turtles, and as such wouldn't be a threat to anyone. They would need to adapt to an herbivore lifestyle because they wouldn't be able t hunt anything. They might also need to spend a lot of their time in water to sustain their own weight.

So all you need to do is to trip them, and their ligaments will tear apart (really, check the link above for a question on giant insect musculature). From there you just need a mallet to gain access to their tasty insides.


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