Notable animation sequences from Firth include Salad Fingers, as well as the comedic Burnt Face Man series. A number of Firth's works have been featured on the BBC in the UK, and the BBC has hired Firth on several occasions to work on TV programs and commercials. He also created a flash-series called "Jerry Jackson", which can both be viewed on Newgrounds and his own site, in which a cartoon character ironically pretends to be "a professional animator", even though the animation is intentionally poorly crafted. Jerry Jackson was also based on the people who would write badly written hate comments on his videos, as he would read them, he imagined that they spoke like Jerry Jackson. Firth also created Men from Up the Stairs, and wrote and animated his Sock series, based on his own dreams.
Firth's work often contains a large amount of dark imagery and tends to explore topics of a disturbing or surreal nature, such as depression and mental illness. Firth has stated that it is not his intention to upset or offend. Some of his work may be described as dark humour, while much of it is simply experimental, using many different styles.
Firth is a fan of Aphex Twin, and has used references such as the song "Milkman" in a cartoon also titled "Milkman". Also, in the cartoon "Scribbler", an Aphex Twin poster can be seen. Firth has also used music by Aphex Twin in his more experimental, stop-motion films.
In addition to several broadcasts of "Devvo," David Firth has produced short films for "Charlie Brooker's Screenwipe", televised on BBC Four.
Firth composes electronic music under the pseudonym of Locust Toybox. He is currently working on his first animated feature film, currently titled "The Meadow Man". Firth believes the title will eventually change, though has said that for now it is the official title, as well as more of his small cartoons, such as another Health Reminder. Firth also plays lo-fi pressure-pop music under the alias Stegosaurus Trap, and is a member of a band called Grape Digging Sharon Fruits with friends and contributors to his projects.
He is currently hitchhiking around England and going to the following countries: Sweden, Denmark, Germany, the Netherlands, Austria, Italy, Slovenia, Czech Republic, France, Switzerland, and Croatia." - Wikipedia quote