red spider

US /ˌred ˈspaɪ.dər/
UK /ˌred ˈspaɪ.dər/
"red spider" picture
1.

ragnetto rosso

a tiny red or reddish-brown mite that feeds on the sap of plants, often causing damage to crops and garden plants

:
The leaves of the rose bush were covered in tiny red spiders.
Le foglie del cespuglio di rose erano coperte da minuscoli ragnetti rossi.
You need to treat your plants for red spider infestation.
Devi trattare le tue piante per l'infestazione da ragnetto rosso.