The developmental pattern of leg paralysis in Lucilia sericata (Meig.) induced by 0.3 µl Risella 1 7 oil (applied topically) was observed to differ according to whether the appendages belong to the fore-, mid-, or hindlegs. In general the forelegs were least susceptible and the number of paralytic legs increased with time. By 3 days after treatment most of the affected flies had 3-4 legs paralysed. Also evident is a strong association between the type of paralytic symptoms and the kind of appendages.