Who's saying they need to fight 1 to 1? If they hadn't taken their sweet time, it's possible the mind reader hadn't hatched yet. They only knew of Neferpitou from Killua's report, so they could have tried to see if just a single enemy had stepped out if provoked (they would have known from Killua's report that Neferpitou is eager to seek a fight). Even if it's two now, it would still be 3 to 2, not such bad odds. However, even they know the odds are only getting worse. This doesn't make much sense if you ask me.

But then again, I still think they should get a bomber to drop canisters of pyrethrin around the nest. Maybe even DDT for good measure, since this is but an isolated case. At the end of the day, it's still insects they are fighting. Why make such a big deal out of it?