Four factors that affect oviposition behavior of Dendroctonus ponderosae Hopkins in lodgepole pine, Pinus contorta Douglas, were investigated. These were distance between egg galleries, size of the female, phloem thickness, and temperature. The average number of eggs oviposited per inch of gallery increased with increases in each of the 4 factors. The average number of eggs oviposited per day also increased with increases in each factor except that the effect of distance between galleries was not investigated. The rate of gallery construction increased only with an increase in temperature; it was unaffected by size of female and phloem thickness. Again the effect of distance between galleries was not investigated.