A concerned reader Mr Jason Phoon sent in a photo of tiny insects to askST. Mr Phoon, who lives in Ang Mo Kio, spotted these critters in his daughter's room: "They were crawling all over the walls and number in hundreds.
"They are very small, around 2mm or smaller in size.
"Please enlighten me what they are and whether they are dangerous to humans.
"Please also advise me how to deal with them if possible.
"Hope to hear from you soon as I'm worried for my family's health, especially my nine-year-old daughter."
Environment reporter Audrey Tan got help from an entomologist to identify the insects.
These harmless insects are known as booklice, and are neither poisonous nor venomous, said Dr Ang Yuchen, an entomologist (insect researcher) from the National University of Singapore.
Booklice such as those pictured should not be confused with lice, which are parasites of humans and other warm-blooded animals, Dr Ang told askST.
Booklice are harmless scavengers that feed on mould in the wild.
They have a preference for the glue used to bind books in our homes, hence their name, Dr Ang said.
Other than books, booklice can also infest dried starchy foods that have become damp - and will thrive as long as there is moisture and darkness.
"Having so much booklice usually means that the place is damp, which encourages mould growth for the booklice to feed on," Dr Ang added.
His advice for controlling the population is a thorough spring cleaning, and ensuring that the place is not too damp.
More askST stories here.