Cafard vs. blatte vs. cancrelat

In the French language, various terms describe the insect commonly known as the 'cockroach'. Three such terms are 'cafard', 'blatte', and 'cancrelat'. Although they all refer to similar creatures, there are subtle differences in their usage and connotations.

Cafard

While 'cafard' can mean 'cockroach', it is a colloquial term that also refers to a feeling of melancholy or depression.
J'ai un cafard dans ma cuisine.
(I have a cockroach in my kitchen.)
Il a un cafard depuis hier.
(He has been feeling blue since yesterday.)

Blatte

'Blatte' is the scientific and neutral term for 'cockroach' in French.
Les blattes peuvent survivre sans tête pendant une semaine.
(Cockroaches can survive without a head for a week.)
Cette blatte est résistante aux pesticides.
(This cockroach is resistant to pesticides.)

Cancrelat

'Cancrelat' is another word for 'cockroach' that tends to evoke a particularly strong disgust or revulsion.
Les cancrelats envahissent souvent les vieux bâtiments.
(Cockroaches often infest old buildings.)
Personne n'aime voir un cancrelat chez soi.
(Nobody likes to see a cockroach at home.)

Summary

While 'cafard', 'blatte', and 'cancrelat' can all refer to a cockroach, 'cafard' is more often associated with feelings of sadness and is used informally. 'Blatte' is the scientific term used without emotional connotation. In contrast, 'cancrelat' highlights the repulsive aspect of the insect, usually invoking stronger feelings of disgust.