Abstract: A survey was undertaken to study the distribution and nature of infestation of L. viridissima and O. monoceros in four oil palm plantations in Cross River State, Nigeria. The results showed that while O. monoceros was fairly prevalent across the three agro-ecological zones of the state, L. viridissima was low in numbers except at Ibiae and Boki plantations where outbreaks was recorded. The mean number of O. monoceros was 13.8 per block in Ibiae, 16.4 in Boki, 13.4 in Calaro and 15.8 in Nsadop oil palm plantations respectively showing no significant differences (p>0.05) among the plantations. However, there were significant differences (p<0.05) in the mean number of L. viridissima with 18 per block in Ibiae, 10.8 in Boki, 6 in Calaro and 5.2 in Nsadop. O. monoceros and L. viridissima are potential and occasional pests of the Cross River State oil palm estates respectively and if left unchecked could result to economic pests injuries by way of outbreak populations. Studies on the growth stages of L. viridissima under laboratory conditions showed that, the entire developmental period from egg to adult was between 86-123 days (mean 98 days).