Opsiphanes cassina
is a defoliator insect that causes economically important losses in oil palm plantations (
Elaeis guineensis
Jacq.). In order to implement timely control measures, with minimal environmental damage, it is essential to
estimate the population size, which normally is realized throughout weekly counts on leaf 17 or 25 of two palms ha
-1. At
the farm "Agropecuaria El Aguila", Monagas state, Venezuela, evaluations were realized aimed to developing a sampling
method to quantify the immature stages, discriminating its preference on the different sections of the leaf. Between August
2001 and August 2002, a lot of 10 hectares of oil palm were evaluated. Weekly, the leaf No. 25 was sectioned from two
trees per hectare. It was determined that the immature stages of the insect showed a clear tendency to be located in the
subapical section of the leaf (pairs of leaflets 41 to 80). In general, the oviposition occurred in the pair of leaflets 71, while
larvae instars I and II were held between the pairs of leaflets 71 and 73, larvae III and IV were located on the pair 68, while
the instars V was located on the pair of leaflets 61. Process of pupation occurred preferentially in the stipe of the plant.
When it occurred in the leaf it had predilection by the pair of leaflets 43. The new strategy to sampling immature stages of
the
O. cassina suggests focusing the efforts on the subapical section of the leaf.