It's a floored fly, also known as a coffin fly.

这是一种落地苍蝇，也被称为棺材苍蝇。

Blow flies will lay eggs on the zip and the female of coffin flies can pass through the zip and reach the body.

吹蝇会在拉链上产卵，棺材蝇的雌性可以穿过拉链到达身体。