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A second possibility is that mosquitoes maintain a local presence and survive during the dry season, hidden away in a state of dormancy termed aestivation.

Alternatively, the insects might spend the dry season in aestivation, a unique type of dormancy that occurs in some animals that need to survive long dry seasons.

Of the physiology of aestivation nothing definite appears to have been ascertained.

A second factor is the availability of necessary shelter, especially aestivation sites.

This habit is doubtless of value, especially during hibernation or possibly during the summer lethargy or aestivation, the latter a habit which may be more general among these butterflies than is now supposed.