"These different demigods, or directors, such as Candra, Varuna and Vayu, are called adhikari-devata. The demigods are departmental heads. The government of the Supreme Lord consists not only of one planet or two or three; there are millions of planets and millions of universes. The Supreme Personality of Godhead has a huge government, and He requires assistants. The demigods are considered His bodily limbs. These are described in Vedic literature. The sun-god, moon-god, fire-god and air-god are working under the direction of the Supreme Lord. It is confirmed in the Bhagavad-gita (9. 10), mayadhyaksena prakrtih suyate sa-caracaram. The natural laws are being conducted under His superintendence. Because He is in the background, everything is being performed punctually and regularly."
"The administrative posts occupied by the demigods for maintaining the regulations of the material world are offered to the highly elevated pious living beings. When there is a scarcity of such pious living beings, the Lord incarnates Himself as Brahma, Prajapati, Indra, etc., and takes up the charge.
Srimad-bhagavatam 1:3:12 Purport
"Factually there is no need of offering sacrifices to the demigods for their services if one is engaged in the service of the Supreme Lord. Sacrifices recommended in the Vedic literature for satisfaction of the demigods are a sort of inducement to the sacrificers to realize the existence of higher authorities. The demigods are engaged by the Lord as controlling deities of material affairs, and according to the Bhagavad-gita, when a demigod is worshiped the process is accepted as the indirect method for worshiping the Supreme Lord. But when the Supreme Lord is worshiped directly there is no need of worshiping the demigods or offering them sacrifices as recommended in particular circumstances."
Srimad-bhagavatam 2:7:32 Purport
"In the Bhagavad-gita, worship of different demigods or rendering service to them is not approved. It is stated in the Seventh Chapter, twentieth verse:
kamais tais tair hrta-jnanah
tam tam niyamam asthaya
prakrtya niyatah svaya
"Those whose minds are distorted by material desires surrender unto demigods and follow the particular rules and regulations of worship according to their own natures." Here it is plainly said that those who are directed by lust worship the demigods and not the Supreme Lord Krsna. When we mention the name Krsna, we do not refer to any sectarian name. Krsna means the highest pleasure, and it is confirmed that the Supreme Lord is the reservoir or storehouse of all pleasure. We are all hankering after pleasure. Ananda-mayo 'bhyasat (Vedanta-sutra 1.1.12). The living entities, like the Lord, are full of consciousness, and they are after happiness. The Lord is perpetually happy, and if the living entities associate with the Lord, cooperate with Him and take part in His association, then they also become happy.
The Lord descends to this mortal world to show His pastimes in Vrndavana, which are full of happiness. When Lord Sri Krsna was in Vrndavana, His activities with His cowherd boyfriends, with His damsel friends, with the inhabitants of Vrndavana and with the cows were all full of happiness. The total population of Vrndavana knew nothing but Krsna. But Lord Krsna even discouraged His father Nanda Maharaja from worshiping the demigod Indra because He wanted to establish the fact that people need not worship any demigod. They need only worship the Supreme Lord because their ultimate goal is to return to His abode."
"All the controlling deities like Visnu, Brahma and Siva are different manifestations of the Paramatma feature of the Supreme Personality of Godhead Sri Krsna, who exhibits himself in such manners by entering into each and every universe generated from Him. But still apparently there are divisions of the controller and controlled. For example, in the food-controlling department the controller of food is a person made of the same ingredients as the person who is controlled. Similarly, each and every individual in the material world is controlled by the higher demigods. For example, we have our senses, but the senses are controlled by superior controlling deities. We cannot see without light, and the supreme controller of light is the sun. The sun-god is in the sun planet, and we, the individual human beings or any other being on this earth, are all controlled by the sun-god as far as our eyes are concerned. Similarly, all the senses we have are controlled by the superior demigods, who are also as much living entities as we are, but one is empowered while the other is controlled. The controlled living entity is called the adhyatmic person, and the controller is called the adhidaivic person. All these positions in the material world are due to different fruitive activities. Any individual living being can become the sun-god or even Brahma or any other god in the upper planetary system by a higher grade of pious work, and similarly one becomes controlled by the higher demigods by lower grades of fruitive activities. So every individual living entity is subject to the supreme control of the Paramatma, who puts everyone in different positions of the controller and the controlled."
Srimad-bhagavatam 2:10:8 Purport
Bhaktivedanta Book Trust. HDG A.C. Bhaktivedanta Swami Srila Prabhupada.