Waspberry Jam

Wondrous item, common
  This terracotta jar, 4 inches in diameter, contains 1d4 + 1 doses of a sweet, sticky, pink jam. The jar and its contents weigh ½ pound.
  As an action, you can spread a single dose of jam to cover a 5-foot-square area. Immediately, Tiny, venomous waspberries teleport from the fey plane forming a swarm of insects. A creature that starts its turn in the swarm’s area or enters the area for the first time on a turn must make a DC 11 Dexterity saving throw, taking 2d4 piercing and 2d4 poison damage on a failure or half as much damage on a success. If the swarm has half its hit points or fewer, the damage is reduced to 1d4 piercing and 1d4 poison.
  It takes the swarm one hour to completely consume the jam, after which it returns to the fey plane. The swarm does not like smoke. If the area where the jam is applied is ever covered in heavily obscuring smoke, the swarm teleports back to the fey. If the smoke disappears, the swarm immediately returns to continue eating the jam.