I did use Lemongrass oil - just some bog standard one from Amazon. A few weeks ago both bait hives were reasonably active then it all died off for about 7 to 10 days. The first bait hive to attract a swarm (Monday) had been very busy for about 3 days. It's hard to quantify as you never know how many are inside but I'd say around 30 to 50 pretty constantly, There were regularly around 10 to 15 on the face of the hive. It slackened off the morning of the day they arrived.
The second hive was busy, but nothing like the first one. As a result I did not expect to see a swarm arrive. It had it's moments but generally I'd say 15 to 30 bees hanging around. I think it's the bigger of the two but haven't opened up yet. Will probably move it Saturday, and then open it to transfer to a hive Monday / Tuesday. This bait hive hadn't had the lemongrass inside the box renewed since it went up about 5 weeks ago.