Do insects have souls like humans, and if they are killed, will one be held accountable for it? And is it permissible to cover drinking vessels out of fear of the devil?

Animals have souls that the Angel of Death seizes by Allah's permission. The ruling on killing insects differs: it is recommended or obligatory to kill those that are harmful, and prohibited to kill those that are not harmful, unless there is a need. Whoever kills them unintentionally bears no sin.