Studies about Dermatobia hominis larvae have been described, but no data were found regarding dairy cattle from organic production system in tropical region. The herd consisted of dairy crossbred zebu x taurine. Fortnightly inspection inspections with mapping for the presence of larvae in the body surface was carried out over the period of a year in the area of the Integrated "groecological Production System -I"PS/RJ -a technical cooperation project. The results indicated predominance of parasitism in females average . . In males, the highest number of nodules were on the right side . in females, highest number of nodules were on the left side. The infestation in adults average .was highest animals in lactation were less infested average . in young animals, the most infested side was the left the most infested coat was the black on white average . the less infested coats were red with typical shades average . and light brown and dark . . Each increment of mm ³ of water caused a mean increase of . in the relative risk of occurrence of dermatobiosis and with every one degree increased there was an average increase of . in the relative risk for infestation.