METHOD OF FIGHTING AGAINST INSECTS INCLUDING THE USE OF A HYDROCARBON COMPOUND MIXTURE CHOSEN AMONG ALKANES OR ALKENES COMPRISING FROM 20 TO 40 CARBON ATOMS.HYDROCARBON COMPOUND MIXTURE ACCORDING TO THIS INVENTION. INSECTICIDE COMPOSITION INCLUDING A HYDROCARBON COMPOUND MIXTURE ACCORDING TO THE INVENTION IN MIXTURE WITH ONE OR SEVERAL INSECTICIDE COMPOUNDS. METHOD OF TREATMENT AGAINST INSECTS WITH AN EFFICIENT QUANTITY OF SUCH COMPOSITION.