How to migrate vApp to another Host ?

We have imported vApp for Operations Manager.  There are 2 VMs in that vApp.

We just wonder how to migrate the vApp to another ESX Host ?  We find that we can migrate individual VM but not the vApp.  Is my understanding correct ?

Moreover, when the ESX Host goes to maintenance mode, the vApp (or that two VMs) does migrate to another ESX host.

Your advice is sought.

Thanks