Staff of Swarming Insects

This staff has 10 charges and regains 1d6 + 4 charges daily. If you expend the last charge, roll a d20. On a 1, the staff is destroyed.
While holding the staff, you can use an action to expend some of its charges to cast one of the following spells from it, using your spell save DC: giant insect (4 charges) or insect plague (5 charges).
Insect Cloud. You can use an action and expend 1 charge to cause a swarm of harmless flying insects to spread out in a 30-foot radius from you. The insects remain for 10