Rapid estimation of numbers of whiteflies (Hemiptera : Aleurodidae) and thrips (Thysanoptera : Thripidae) on sticky traps

The presence or absence of greenhouse whiteflies, Trialeurodes vaporariorum Westwood, and thrips, primarily western flower thrips, Frankliniella occid entalis (Pergande), in cells of a grid laid over 7.6 cm by 12.7 cm sticky t raps was used to estimate the population density of these pests on the trap . The method accurately predicted trap population densities of between 15 a nd 192 individuals per side for thrips on blue and yellow traps and between 15 and 168 whiteflies per side on yellow traps. The distribution of both w hiteflies and thrips tended to be clustered on the sides and upper edge of the traps. The method is useful in giving a far more rapid estimate than co unting individuals, particularly at high population densities.