My tips:
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Along with these tips I recommend playing on Haz 2 or 3. Haz 1 has basically no bug spawns so I would avoid it.
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Try get a mission that has one large open cave area like Refining or Extraction. I did mine on a Salvage mission.
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Along with 4 Scouts, make sure to remove ALL AoE effects like cryo grenades, shield explosions etc. Slow grenades and the boomerang are great choices to keep bugs at a distance.
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Make sure to take out any praetorians or oppressors before getting on the harvester.
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This strat is pretty risky but worked great for us. On Salvage, you can begin the uplink section to get a bunch of bug spawns. Keep a dwarf on the harvester to keep track of the bugger, and have the other 3 making progress on the uplink while training the bugs. Once the uplink is at around 80-90%, make a mad dash to the harvester and try get the achievement done before the uplink ticks down to zero.
Hopefully this helps, good luck :)