The aphelinid genus Aphytis contains the most important natural control agents of numerous armored scale insect pests. The genus consists of several species groups, including the lingnanensis group. This group has several sibling or near-sibling species which are exceptionally useful in biological control.

Accurate identification of these parasites is supremely important in biological control, but this is often difficult when sibling or cryptic species are involved, as morphological characters used to discriminate taxa are absent. Therefore, studies were conducted to determine the feasibility of using behavioral characters for the separation of such species in the lingnanensis group.

Qualitative analysis of courtship behavior revealed that it is possible to separate A. lingnanensis from A. melinus DeBach, A. holoxanthus DeBach, A. fisheri DeBach, and a semispecies of A. melinus, on the basis of overt male behavior and female response to male behavior.

Quantitative analysis of 16 cultures in the lingnanensis group showed that it is possible to identify different species by using precoital courtship duration, postcoital mount duration, precoital wing vibration pulse frequency, postcoital wing vibration pulse frequency, number of contacts between the sexes, and number of male courtship attempts, as characters. In some instances, the parameters tested are useful in grouping allopatric populations of a species.

Some antennal ablation experiments were done and antennae were chemically treated to determine their role in courtship. These studies indicated that antennae are essential for successful copulation.

Scanning electron microscope studies revealed a mesothoracic