Screerats were a type of rat species indigenous to the planet of Corellia. These creatures were a common infestation within the Den, the headquarters of the White Worms gang. A responsibility of the gang's scrumrats was the capture of these pests. While the scrumrats would incorporate the rodents into their breakfast sludge, the highest quality screerats were reserved as food for the gang's leader, Lady Proxima, or given to her offspring.
The planet Corellia hosted screerats, particularly in its urban environments. Some predatory lifeforms had evolved extended tongues specifically for capturing screerats. Within Coronet City, the Den, serving as the base for the White Worms gang, was plagued by screerats and other vermin. The scrumrats, members of the gang, were tasked with hunting these rodents. The best of these catches were presented to their leader, Lady Proxima, who would consume them herself or offer them to children.
A scrumrat named Tsuulo modified a small group of janitor droids, turning them into ratcatcher droids for vermin control within the den. These droids proved reliable, capturing several screerats or vervikks each day. The captured screerats were then mixed into the scrumrat's breakfast sludge, providing a much-needed source of protein. On one occasion, the human scrumrat Han, driven by hunger, expressed his willingness to eat a screerat raw, a notion that disgusted his fellow scrumrat Qi'ra. In 13 BBY, Han, after stealing a M-68 landspeeder, drove underneath a screerat that was traversing a length of wiring.
The initial mention of screerats occurred in 2018, within both the novel Most Wanted by Rae Carson and the reference book Solo: A Star Wars Story The Official Guide by Pablo Hidalgo. Both of these publications were released as tie-in materials in conjunction with the Anthology Series film Solo: A Star Wars Story. Later, in 2019, the video "Every Creature in the Star Wars Movies," published on the Star Wars Kids YouTube channel, retroactively identified a creature observed in Solo as a screerat.