Locust having a connection to Fami and it eating up a lot of devils to get stronger makes a lot of sense why it could jab Yoru like that. That or she's pretending.
If that was all it took it would have done that a long time ago. There's a theory that since Pochita gobbled Death, creatures that multiply quickly (like insects) are now the scariest things, seeing as they don't die and keep multiplying forever. That or Fami got a major boost (no death means eternal hunger, if something eats you you're still alive, etc). In any case several weird things in this chapter point to something major having changed:
- hell is essentially empty (Denji says as much), this probably ties into the missing devils in Denji's barf from last chapter
- Yoru is weakened (her bang attacks did almost nothing to Denji and she got one-shotted by Seraphim)
- locust devil (and possibly others) is way more powerful than it should be (even taking into account Yoru is weakened, Seraphim managed to take off Denji's arm so it's strong on its own). Or maybe it's Pestilence devil rather than locust, which would maybe make it another horseman?
I don't see what else could have caused mass devil extinction and power upheavals like that other than Death being erased. Then again, I doubt death, as a central concept to human life, can stay erased for long. If it took only a few months or so for Control to reincarnate, Death could already be revived. Also Yoru did say Death's power awakens if she dies, but she didn't just die but was rather erased, so that probably doesn't come into play here.
Good chapter good stuff. Morons still gonna moan about part 1 tho