In French, dusk can be described as "entre chien et loup", which means "between dog and wolf" - the hour of the day when one cannot distinguish a dog from a wolf.
Another phrase that is mentioned in Rant is "la nuit, tous les chats sont gris", which means "every cat is grey in the twilight".
In the 1898 Dictionary of Phrase and Fable, a "Blindman's Holiday" is defined as "The hour of dusk, when it is too dark to work, and too soon to light candles." "Owl-light" is another phrase for dusk and a quote is also provided, “The best time to talk of difficult things is entre chien et loup, as the Guernsey folk say.”—Mrs. Edwardes: A Girton Girl, chap. xlvi.
Entre chien et loup: A Study of French Animal Metaphors in The French Review: Vol. 63, No.3, February 1990, has a list of metaphors, such as "peigner la girafe" (literally: "to comb the giraffe"), which means "to waste time on a pointless task".
The list of French expressions you won't learn at school.. also contains some cool phrases like "Tirer des plans sur la comète - To build castles in the air (literally: "to draw plans on the comet")".
I better get back to combing the giraffe and drawing plans on comets, before it is the time between dog and wolf.