This proverb indicates that while it is easy to think of oneself as indestructible or free from problems, one must not ignore the small things that can cause trouble. Just as the sky, which appears vast and unmovable, does not collapse, small concerns or little creatures like mosquitoes can still create nuisances. In other words, do not ignore small problems thinking everything is fine. An equivalent English proverb would be ‘The devil is in the details.’