Mosquito

1. [impulse] /scoreboard objectives add timer dummy

2. [impulse] /give @p minecraft:vex_spawn_egg[minecraft:entity_data={id:"minecraft:vex",Tags:["mosq"],attributes:[{id:"minecraft:scale",base:0}],Silent:1b,life_ticks:1200,active_effects:[{id:"minecraft:invisibility",amplifiler:1,duration:-1,show_particles:0b}]}]

3. [repeat] /execute as @e[tag=mosq] at @s unless entity @e[tag=mosqBlock,distance=..0.25] run summon minecraft:block_display ~-.03 ~ ~-.03 {Tags:["mosqBlock"],transformation:{left_rotation:[0f,0f,0f,1f],right_rotation:[0f,0f,0f,1f],translation:[0f,0f,0f],scale:[0.0625f,0.0625f,0.0625f]},block_state:{Name:"minecraft:gray_concrete"}}

4. [chain] /execute as @e[tag=mosqBlock] at @s unless entity @e[tag=mosq,distance=..0.25] run kill @s

5. [chain] /execute as @e[tag=mosq] at @s if entity @e[type=minecraft:player,distance=..2] run playsound minecraft:entity.bee.loop_aggressive ambient @a ~ ~ ~ .5 2

6. [repeat] /execute as @a at @s if biome ~ ~ ~ minecraft:plains run scoreboard players add @s timer 1

7. [chain] /execute as @a at @s if score @s timer matches 20 run execute store result score @s timer run random value 21..25

8. [chain] /execute as @a at @s if score @s timer matches 21 run summon vex ~ ~5 ~ {Tags:["mosq"],attributes:[{id:"minecraft:scale",base:0}],Silent:1b,life_ticks:1200,active_effects:[{id:"minecraft:invisibility",amplifiler:1,duration:-1,show_particles:0b}]}

9. [chain] /execute as @a at @s if score @s timer matches 20.. run scoreboard players set @s timer 0