OP did manage to clarify that that is a full jug of milk in the mosquito bath ... but many questions remain.
I would argue that just makes it weirder
If the waters cool it might be slowing it from warming too fast if they can't get to a fridge right away
Please explain the distracting detail in a comment below. Failure to do so may lead to removal of your post.
I am a bot, and this action was performed automatically. Please contact the moderators of this subreddit if you have any questions or concerns.