It is well known that female ixodid ticks undergo salivary gland degeneration and the greater part of ovarian development following engorgement. The process has been particularly well studied in Amblyomma hebraeum, including the hormonal control of these processes. The purpose of this study, and the second one in this series, is to compare the processes in Dermacentor andersoni with those of A. hebraeum. A major difference between the two species is that virgin female D. andersoni feed to a much higher fed-to-unfed weight ratio than do virgin female A. hebraeum, the former achieving an average of 67× the unfed weight in this study, the latter normally achieving an average of only about 10-15× the unfed weight. We show here that although engorged virgins (defined here as those that exceed a fed-unfed weight ratio of 50, even though they do not detach from the host spontaneously) degenerate their salivary glands and develop their ovaries, these processes proceed more slowly in virgins that they do in mated females, as is the case for A. hebraeum.