Note: I correct the given mistake only once. If you do not use the metric system, I will only make a single comment about it, even if it appears again in the rest of the article. If the draft has many language problems, I will only correct the most glaring ones.
One(1) hive of SCP-xxxx will be kept in a 5x3x5m containment chamber for testing purposes.
While the number (#) notation saw a lot of use in the past, it's not something that really needs to be used unless there's a strong need for the number to be read accurately (drug dosages, for instance.) Otherwise it's just taking up space. Measurements shouldn't be included unless they are essential to containment. E.g., it's okay to say 'standard' and you don't need to include the measurements at all, as that can actually cause more trouble and questions more often than not.
Instead of biting prey
You mean stinging?
it does appear to diminish neural capabilities
Instill drowsiness and inhibit alertness?
and attract prey in a manner that compels them to follow trails of the pheromone.
I'd change this into: 'capable of mimicking pheromones of the respective species' because the word 'compulsion' has a negative bias attached to it.
Once SCP-xxxx-1 and the swarm arrives, a new kind of bee comes into play.
Don't say 'come into play'. It's unclinical.
SCP-xxxx "butcher" bees are nearly twice as large as workers, coming to a average length of 2.5 inches.
Since the Foundation is an international organisation, we use the metric system. Use metres, centimetres and kilometres.
SCP-xxxx "butcher" bees are nearly twice as large as workers
You should probably designate these 'butcher' and 'worker' bees as SCP-XXXX-1 and -2 while making prey animals -3.