Spider venoms have high specificity to neuronal elements. Therefore, the use of venom has been important in the characterisation of mammal and insect nervous systems. The evaluation of insect paralysis has been an important tool for distinguishing the biological effects of venom. In this study we describe the paralysing effect of a spider crude venom (Parawixia bistriata) in termites, utilising a new bioassay. The crude venom of P. bistriata caused an irreversible and dose-dependent paralysis in the animals in the following doses: 2.10(-5) U; 2.10(-4) U; 2.10(-3) U; 2.10(-2) U and 0.12 U (1 U = 1 gland). This bioassay will allow for easy and direct evaluation of biological effects from different venoms and purified fractions.