Note: The mature tag is because I draw and describe (..and make a joke about) their internal genitalia. I also describe other gross stuff, like digestive systems, and I mention things like cannibalism. So I added it just in case someone here is uncomfortable with anything like that, to give you a fair warning about it. I have titles for each part, so just skip those bits you think you don’t want to read :)
 
And the next part is finished! It would have been up much earlier, except I decided that since I split it up, I now have so much more space! For even more info! Let’s add a diagram of the internal organs I previously had only written about, and let’s add some even more text while we’re at it!
 
I am very predictable I fear.
 
I also fear what anyone seeing my internet history would say. Ah, yes, there she spend several hours looking at how a spermatheca works.
 
Biology  
Exoskeleton and external structures  
Like their ancestors, they still have an exo-skeleton. Not naturally smooth in texture, but they often “polish” themselves to appear shinier. They have a hard shell on their back, which they keep their wings under. Like some beetles, their wings are larger than what should be able to hide under the shell, so they fold them up to make them fit.
 
The underside of their thorax is covered by segmented chitin, which is overlapping and somewhat flexible and can therefore allow the thorax to expand. This is because as they no longer have an abdomen, their eggs are now stored in the modified thorax - which will then need to be able to grow in size to fit them.
 
They only have two pair of legs left; the middle pair made it more difficult to keep the illusíon, so they were reduced. You can still see some remnants of internal musculature under the chitin where they used to be. The legs they have left are thick and mimic pony-legs in structure, ending in hoof-looking feet. They have small bumps/claws at the end to help with grip.
 
 
Head and Face  
Their “horn” is modified antennae, and it is the main channel they use to control their magic. It’s inflexible and covered in this chitin to protect it. Their “ears” are more like traditinal anntennae; used to smell/“taste” and to sense air-pressure, winds, heat and so on.
 
The Queen has extra anntennae for better communication with the hive-mind, often appearing similar to deer horns. This lets them navigate the flux of impressions better, and steer it in certain directions.
 
They have compound eyes, which are usually colored dark. On those with lighter colored eyes, you might see a pseudopupil. They have specially developed tissues which can cover the eyes, in order to mimic pony eye-lids. It’s easier to actually physically “blink”, and move the illusion along, than to just have the illusion do it.
 
Their mouth is very sharp and beak-like, to snip of bites and cut stuff with. Inside the mouth, what used to be their mandibles are kept flat againt the roof of their mouth, to resemble teeth. They can still be moved and extended outside of the mouth. It’s good for grabbing and carrying things, so they don’t have to waste energy lifting things in their magic. They would just carry them in their mouths like ponies do… except, as mentioned, sharp beak.
 
Since their mouth isn’t connected to their repiratory system, they can’t make very complex sounds. It’s limited to whistles, chirps and clicks, which are done by rubbing or clacking together parts in their throat. This means that can’t actually speak most languages - instead, they chirp and whistle and magically convince the listener that they’re hearing words.
 
 
Breathing and transporting oxygen  
One of the first mutations Discord made to their ancestors so that they would survive being scaled up, was that they developed lung-like structures. Their bug-sized ancestors instead had tracheae, which were tubes running through their body; the air entered into these tubes through holes in the abdomen. This, however, only works because they were small enough; in order for insects their current size to breathe like this they’d need a much higher oxygen content in the air. (That’s why there once lived giant insects here on earth, but only small ones survive today; the air used to have a much higher concentration of oxygen.)
 
So Discord’s magic modified some of the tracheae’s air-sacks into into “lungs”. Originally, they still breathed through their abdomen, through two holes on either side. But as it grew into the tail-like structure they now have, the holes moved to right where the “tail” meets the thorax. You could say, they breathe through the top of butt.
 
Since the air then isn’t moved thoughout the body via the tracheae, their blood was also modified to move oxygen and carbon dioxide. They use something similar to hemoglobin to bind the oxygen, so their blood is colored brightly red. (It’s very similar to bloodworms’ blood!)
 
The were also changed to have a closed circulatory system. Their heart still retain the some of general shape of the heart they had when it was an open system, but it now pumps the blood through blood-vessels; going from the heart, past the lungs where it’s oxygenated, back to the heart and then out into the body, before returning to the heart - pretty much like how it works in birds and mammals. They also has four “chambers” - though, unlike birds and mammals where it’s one heart with four different sections, a changeling has two hearts, with two sections (the two center hearts) and two extra large muscle pumps (one on each side) that helps push the blood.
 
It’s also worth mentioning that they are “endothermic” - their larger body size and the fact that their prey lives in an environment that has months of average temperatures below freezing, means that is necessary for them to make their own heat. This wasn’t caused by Discord directly, and isn’t achieved the same way mammals or birds do. Rather, once they gained more magic, those who were able to use said magic to generate heat survived better when they followed the migrating horses further up north. The heat is generated in the center of the body, and then transported to the extremities via the blood.
 
 
Digestive System  
Their digestive system is very reduced, since they get most of their energy from emotions. But as mentioned, they still need to eat solids, for “building material” for the body. Since their digestive system is so short and ineffective, they can’t actually extract nutrients from most food, so their solid diet is almost only heavily pre-processed meat. (Morbid fact: Those hives that kidnap ponies and to keep in pods and harvest love from, usually don’t just discard the bodies when the victim dies. You may extrapolate for yourself what they do with them).
 
Fun fact! (Also, gross fact) On their ancestors, their digestive system ended towards the end of their abdomen. But despite how the abdomen shrunk and formed the “tail”, the end of their current digestive system is still at the end of their abdomen. They poop out the end of their tail is what I’m saying. Or rather urinate? It’s both at the same time, very liquid. They still eat mostly emotions, but they need to drink water and eat a little solid food. This waste is mixed well together to prevent… clogging (not a pretty sight when it does happen), and expelled through a hole in the tip.
 
Related to the digestive process; they can use organic material to create a “goop”-like substance. It’s used as building material (glues stuff together) and to create pods - in which grubs are kept, and victims are trapped in. Its made by swalliwing the right ingredients down into what used to be a crop, l on their ancestors, et the enzymes work for a bit, and then hack it up again. Lovely. The goop is runny and gooey at first, but hardens in the air into a plasticky substance which is cut and shaped by the sharp beak. Creating this goop is something only workers and soldiers can do, the “crop” is reduced and unusable in drones and queens.
 
 
Genitalia  
Aside from it moving into the throax, it’s pretty much the same (albeit scaled up a lot) from how it was on their ancestors. Queens have large ovaries and spermatheca, while workers and soldiers have smaller ovaries and vestigial spermatheca. Drones have testes and can fertilise a queen’s eggs.
 
The biggest change is probably that the drones’ testes are placed further out from the center of the body, pretty much pressed up against the exoskeleton on either side. This is in order to keep them cool enough, since changelings have body heat. Since changelings can’t sweat, in hot weather the drones will instictively lick their sides and buzz their wings to evaporate the saliva and cool down. …Drones also get very angry if you jab their sides, which their worker siblings find hilarious.
 
 
Eating Love  
Their main foodsource is love, but they can eat other emotions as well - though, some of them are the equivalent of us eating dry leaves. Positive emotions which are directed at others have the most energy; love (romantic, familial, friendship…), being proud of someone, joy at someones prescense etc. It’s worth noting that while love (and other emotions) give energy, that is all it does. It allows the changeling to move, to keep warm - anything where the energy is used directly. It cannot be used to build muscles or be stored as fat. Energy to matter conversion is out of a changeling’s abilities.
 
Another problem is that emotions are tough to…digest? For lack of a better word. A single changeling needs to use quite a lot of magic to break the emotions down into a form they can actually absorb. The more effective alternative is to play hot potato with the collected love. Each time a changeling pushes the emotion to another they break it down a little bit more (the changeling magic altering it to become more and more like changeling emotions). It’s more time consuming, but uses less magic and energy overall. So as infiltrators return to the hive, they pass on their gathered love to a worker, who passes it to a worker, who… until it reaches the worker responisble for the “messhall”, who then shares it with the gathered hungry crowd. The crowd leaves, another enters, the worker recieves more processed love from the chain, and the cycle continues.
 
The gem-like structures on their neck/chest are actually crystal structures grown by the changeling - a bit like kidney stones, but intentional. Crystalline structures in my nextgen ‘verse have the ability to store energy, which is also what they are used for here. A changeling can only store so much love in themselves, so they store some of it in the gems when harvesting. This allows them to carry more back to the hive. This is also how a single changeling is actually able to carry enough love to feed a small crowd. Changelings grow new ones continuously thoughout their life, and they fall of as they grow too large. Discarded ones are filled with processed love and put into storage for worse days. Normal gems also work for this, but why go mining when your species just make their own?
 
 
Hivemind and psychic powers  
Almost all of a changeling’s magic is centered around manipulating and feeling the mind and emotions of other creatures. This is first and foremost used to trick their prey into believing that the changeling is someone else. The prey will not only see the disguise, they’ll also smell it and feel fur and soft not-exoskeleton-actual-flesh when touching it. The changeling will also make the prey even more in love with whoever the changeling is impersonating. A changeling can do a few simpler spells, such as levitating small objects, but if they need to perform something larger they usually have to find a way of faking it or magically convincing the audience that they did it. A sufficiently powerful changeling can completely supress their prey’s thoughts and feelings, and have full control over them.
 
A changeling can theoretically do this to each other as well, but it’s much more difficult. Changelings are naturally resistant to having their own mind and emotions manipulated via magic.
 
They do however have a hivemind. This doesn’t mean they have one mind which controls everyones bodies, or that they think as one. Rather, it’s a web of knowledge, impressions and feelings. A changeling uses it to have a general feel of what the status of the hive is, or to share valuable information with one another. A changeling can’t usually be forced to interact with the hivemind, it’s not organized enough to overpower form any type of attack and overpower them. The exception to this being the queen, who, as mentioned, can “steer” the hivemind somewhat. They could force it to focus on this one changeling and overpower them. Though, if a queen is bad, the hivemind can subconcously decide to depose of them and push them out of the connection.
 
Each changeling is connected to only one hivemind (or zero). A queen cannot force a changeling connected to another hivemind - since the reason it works is by using the hivemind the changeling is connected to, to force the connection open.
 
Differing appearence  
Different hives vary a lot in appearence, where each hive try to resemble something specific. Usually insects, but a few try to look bird-like or even things like, the ocean. This came to into being as a roundabout way of showing how powerful the hive is. In order to reproduce new changelings, a hive needs to get drones from other hives. By appearing as really specific things, a hive shows that they have been strong/influential enough to be able to pick and choose of the drones from other hives to get the characteristics they needed. Such as the example hive I’ve used here -appearing as lunar moths. The fact that they even managed to get the Queen’s horns modified into lunar moth-looking antennae is really attractive. The other hives want their drones is what I’m saying.
 
On the other end, Thorax’s hive is extremely unattractive; they are both very varying in appearence from one another, and also don’t look like anything much at all. He might be able to claim they were going for a “rainbow”-look and get a little clout among the lower ranking hives.
 
Other species  
This all should not be confused with other species in Entomocuculi which also appear quite different. Entomocuculi Equulidae vary a lot in appearence, but they are all the same species. Other Entomocuculi, which evolved to focus on other prey, are completely different species. Such as Entomocuculi Gryphus or Entomocuculi Bipes which are depicted here. Some of these species are able to have offspring together, and some are not. For example, E. Gryphus is now extinct (happend a few thousand years ago, when griffons underwent a cultural shift towards valuing independence more), but when they were alive they could have infertile offspring with both E. Equulidae and E. Bipes. However, E. Equulidae and E. Bipes are completely unable to reproduce.
 
 
Societal Roles and Social Structures
 
Queens:  
Each hive is lead by one or more Queens, depending on the size. Their job is to be the leader(s) of the hive. Keeping track of infiltrators, managing resources, overseeing the maintentace of the hive etc. If there’s only one they peroform all these duties. If there are more than one queen in the hive, one queen is the main leader, in charge of the other it’s usually easy to tell who they are, since they are bigger than their fellow queens and the others lead specific part so the hive. So for example, one oversees infiltrators, one oversees hive’s defences etc.
 
Queens are also responsible for making new changelings; laying clutches of eggs which the workers take care of and raise the resulting grubs. Queens don’t usually get involved in the actual parenting, they just lay the eggs. They have a …harem, technically, of drones from other hives which sire the eggs.
 
Lastly, Queens manage the hivemind; acting like a centerpoint of the hive’s emotions and impressions, sorting through the information to glean the important parts, and getting a general feel of how the hive is doing. Steering it in the direction they deem best for the hive.
 
Worker:  
Works. Think of a job that isn’t defending the hive, and it’s almost always a worker doing it. They go out and gather love, they build the hive, they raise the grubs, etc and etc.
 
Workers can lay clutches of one or two eggs. But since they lack a functioning spermatheca, they cannot mate with drones.
 
Soldier:  
Many hives only have a few soldiers -if there is peace, soldiers just use up resources without contributing. If the hive feels threatened, more soldiers start to appear as needed. They almost only exist for outside threats, changelings don’t have many internal problems.
 
Soldiers have a very big and thick shell, with small wings hidden under. They can fly, but not as fast or nimbly as the others. The rest of their chitin is heavy and dense, forming a hard armor.
 
Like workers, they can lay one or two eggs, but cannot mate with drones.
 
Drone:  
Drones usually leave their parent hive. They have less magic than their worker and soldier counterparts, but have larger wings and more stamina which allows them to travel longer distances. In some cases they only leave to scout for the hive -locate neighbouring hives, find fresh settlements to infiltrate, see if there’s any new territory to create a daughter hive in etc.
 
Many also leave for other hives. Sometimes they are still connected to their parent hive’s hivemind, in which case they act as “ambassadors” of sorts. In a lot of cases though, they are “traded” to other hives to join that hive’s Queen’s harem. In this case they loose the connection to their parent hive, and instead joins their new hive’s hivemind. These trades happen to formalize treaties, to get drones for ones own hive, in exchange of territory and so on.
 
They cannot lay eggs, but can mate with a queen.
 

 
Gender:  
Most changeling hives don’t have the same concept of a gender binary as ponies (and most humans) do (yes, ponies are aware of the existance of non-binary people, but they still mostly use the binary system as a way of talking and understanding this -hence the term non-binary, someone outside of the binary). Their language has no gendered pronouns, and the closest concept they have to gender is the Worker-Soldier-Drone-Queen roles. As far as they’re concerned, their prey is gendered, and they pretend to have a gender when infiltrating their prey, but they themselves are not prey. Some get very offended if you try to classify them using prey concepts. There’s definently those individuals who still do identify as a certain gender, and will chose to only tranform into diguises of that gender. That’s… usually not very accepted by the hive though.
 
I’ll go more into this if I ever get around to doing that headcanon on Thorax’s hive, but that’s another reason other hives would find his weird and kinda deviant. Since they had no knowledge aside from what Chrysalis told them, and they haven’t had much contact with other hives after that, they’ve chosen to adopt and model themselves after ponies. Thus also adopting their genders, causing many of Thorax’s changelings to identify with and as different “pony” genders. Including himself.
 
 
Communication:  
Inside a hive, much simpler communication (“Move out of my way”, “I am hungry”, “I am hurt”, “Danger approaching”, etc.) is done via the hive-mind. But when it comes to more complex conversation, or communications with other hives, changelings do have their own language.
 
Since their ability to make sounds are very limited, it’s mainly based around body-movements. They waggle-dance. Their ancestors actually did full on ‘running in figure eights while shaking’ to communicate where they’d found new prey. Current changeling language is evolved from this, but they just stand in one spot; a few ““phonemes”” (what do you call the building pieces of a language that isn’t vocal?) might require slight back and fourth movement. Their ““phonemes” are different shaking of their body, some movement of their shell/wings and tail, a few stomps etc. Combine different ““phonemes”” to make different words, like how our vocal language work. This is then accented and given “feeling” via the additions of chirps and clicks. They also have a very simple language or code made from just noise -it’s just for emergency/quick information, so they can’t have complex conversations in it. It’s used for communicating long distances or in low visibility.
 
In those hives that value art, complex dances which are also poetry is very common.
 
They could also do what they do with other creatures, and magically convince other changelings that they are actually hearing speech -but that takes magic, even more than usual since changeling minds are somewhat resistant to their own magic, so it’s very rarely used. Maybe if they need to give complex information but are too hurt to move.