There is a nest in the corner of the balcony, about 30 cm of loess, with small holes in it and no insects moving. Excuse me, what is this building?

The brooding nest of mud bees.

Mud bees put insects into mud nests after anesthesia, lay eggs in the nests, and then seal the mud nests. When the bees in the nest mature, they will break out of the nest and the mud nest will be abandoned.

Mud bees are solitary bees. They are timid and will not attack people unless they are caught. Generally, it is an agricultural beneficial insect. It is not recommended to uproot its unbroken nest. Of course, if it's too ugly, it's okay to shovel it off.

Extended data:

What personal protective measures should be taken to clear the hornet's nest?

1, you must wear anti-bee clothing or chemical protective clothing;

2. Gloves must be worn and the cuffs and neckline should be sealed with tape;

3. air respirator or other isolation masks must be worn.

Overall safety measures required to dismantle the hornet's nest:

1. Before the demolition, the isolation belt should be drawn to evacuate the nearby people and guide the residents to close the doors and windows;

2. Turn off the flashlight during disassembly;

3. Firefighters who have not taken personal protective measures are not allowed to enter the warning zone;

4. The bag containing the hornet's nest should be intact, thick and airtight.