For the purpose of carrying out the provisions of this chapter, the state entomologist with the approval of the secretary of agriculture shall employ, prescribe the duties of, and fix the compensation of, such inspectors, and other employees as needed and incur such expenses as may be necessary, within the limits of appropriations made by law. The state entomologist shall cooperate with other departments, boards and officers of the state and of the United States as far as practicable.