INFEST: It is fine, just that i found it to get a bit too complicated. An alternative could be to treat it like being on fire? An example of that would be: The spell keeps inflicting one point of damage per round until the victim gets rid of them with a successful MOVE roll (slow action), with a negative modification equal to the Power Level. Armor does not protect against this spell. A target may also make an INSIGHT roll when first affected, with a negative modification equal to the Power Level. On a failure, they must try to get the locusts off themselves, otherwise they are not forced to make the MOVE rolls.
THOUSAND EYES: Well, perhaps.. just add some more fluff? I don't know.. it was just a suggestion.. I don't know if it was a good one.
FEED MAGGOTS: Like can you eat worms that has eaten humans, you might as well cannibalize on the human corpses I guess. They are often fresh, if you did the killing. But good for finding putrid corpses and poisonous corpses I guess. That it counts as food instead of meat also makes it interesting. Perhaps you can feed them meat as well as corpses. Turning meat into food, would really only be a good idea if you don't have a chef.
You could also, but I think maybe you should not (as it complicates things), is add that unless you know this spell, you need the COLD-BLOODED talent to not take a damage to Empathy while consuming the raw live corpse worms.
ELYTRA: It is way way overpowered, yeah. Rank 2 "Flight" makes you fly 1 round. Rank 2 "Deer's dash", increases your movement rate by PL for 1 action. I would remove the movement rate to begin with. Then make you perhaps able to hover one zone for a slow action, but taking any damage or not spending a slow action to remain hovering, would immediately make you fall.
SCREECHING HUM: Yeah, it is just a pretty weak base spell. Can be compared to "Horrify", 1 less rank, and no reducing roll. The only downside is that it cannot target multiple creatures, but the damage is split, and now all creatures can resist, so you kind of often do not want that anyway? But in a some rare niche situations, sure, it can perhaps be more useful.
CREATE NEST: It feels way too complicated for a spell. Do you need all the hive sizes? It can turn it into a minigame that only the spellcaster plays, it distracts. There are plenty of ways to solve it, but they may not fit your vision.
SUMMON SWARM: In the book of beasts, an insect swarm has this rule that reads kind of like this: a single attack against the insect swarm can never deal more than 1 point of damage. The only exception is attacks with fire and fire-based magic, which always inflict double damage on the insect swarm. So I think it fits to add this in here as well, for both spells. It still VERY powerful though, you might not just not cast it when your opponents are all equipped with fire based weapons, but those occasions would be rare. Giving it a starting strength of 2 would be balanced I think. It is dangerous then summons can outshine other party members on their own. It will then tank and distract for a few rounds and maybe even deal some damage. Another limit could be to limit this spell to one swarm, casting it again will disburse an other swarm you control. And/or perhaps the swarm is not controlled, and will attack the nearest creature, attacking your allies in the end, making you not want to summon to many of them.
CONSUME: Well "Blood bond" is powerful, but it at least requires a humanoid of your kin as a requirement. Since consume doesn't, you can always push all rolls, like "oh we need to climb a cliff", I'll push my roll. Lets say you take 2 damage to Agility. Then you just consume for 2 rounds, safecasting, with the two WP you gained from pushing and voila you have no damage, so pushing will become a standard tool outside of combat, like always push when you can..
SWARM FORM: You could add the fire penalty mentioned above. But it kind of depends on your world. Since rank 4 spells always would miscast and you would have a hard time to safe cast them, it is really not at all broken. But a mage that could safe cast it, like by having it in a grimoire, would be dangerous without it. The reduced armor rating to zero however compensates a lot, so it doesn't really need more. Swapping the ranks with "Summon swarm", makes less thematic sense, so therefor I wouldn't do it, as "Swarm form" has a more powerful feel to it. But even they are swapped, if a grimoire with safecasting becomes available, you will have an autowin button, with a rank 4 summon swarm, if you could spend every slow action summoning a powerful swarm for 1 WP.. well, you cannot avoid that it has a minimum of a 1/6 risk of miscast at rank 4, so that is at least something.