Both the mosquito and Lord Brahma are living entities in the material world; both are minute sparks and are part of the Supreme Lord. The very short duration of the life of the mosquito and the very long lifetime of Lord Brahma are both awarded by the Supreme Personality of Godhead according to the results of their karma. But in the Brahma-samhita we find it said, karmani nirdahati: the Lord diminishes or vanquishes the reactions of devotees. The same fact is explained in Bhagavad-gita Yajnarthat karmano nyatra: one should perform karma only for the purpose of satisfying the Supreme Lord, otherwise one is bound by the action and reaction of karma. Under the laws of karma a living entity wanders within the universe under the rule of eternal time, and sometimes he becomes a mosquito and sometimes Lord Brahma. To a sane man this business is not very fruitful. Bhagavad-gita (9.25) gives a warning to the living entities: yanti deva-vrata devanthose who are addicted to the worship of the demigods go to the planets of the demigods, and those who are addicted to worship of the Pitas, forefathers, go to the Pitas. Those who are inclined to material activities remain in the material sphere. But persons who engage in devotional service reach the abode of the Supreme Personality of Godhead, where there is neither birth nor death nor different varieties of life under the influence of the law of karma. The best interest of the living entity is to engage himself in devotional service and go back home, back to Godhead. Srila Bhaktivinoda Thakura advised: My friend, you are being washed away in material natures waves of time. Please try to understand that you are the eternal servant of the Lord. Then everything will stop, and you will be eternally happy.