Many beneficial arthropods exhibit life-history omnivory (Polis & Strong 1996), in that they include honeydew, floral nectar, extra-floral nectar and/or pollen in their immature or adult diet (Hagen 1986; Coll & Guershon 2002). Access to these resources may increase the abundance and rate of parasitism and predation by these arthropods. Carbohydrate and/or protein mixtures, such as Amino-Feed UV' Envirofeast' and Pred-Feed' can be applied to cotton crops to act as artificial supplemental food sources for beneficial arthropods. The rationale is to improve the synchrony of beneficial and prey or host populations in time and space (Hagen 1986) by one or more of the following: increased immigration and lowered emigration rates of beneficial arthropods (Evans & Swallow 1993; Evans & Richards 1997; Mensah 1997); consumption of the supplement by beneficial arthropods, leading to higher survival and/or reproduction (MCEwen et al 1996); higher parasitism or predation rates (Mensah & Singleton 1999, but see McEwen et al. 1996); and reduced number of eggs laid by pest arthropods (Mensah 1996). Field testing of artificial food supplements in cotton has focussed on targeting a few pest species (mostly heliothis), usually with multiple treatments (range I to 13) applied at 7 to 14 day intervals up until flowering or early boll filling growth stages (i. e. , until January or early February) (Mensah 1997, 2002a; Mensah & Singleton 2002). The early to middle part of the growing season was often targeted because pest densities were typically low to moderate (which leads to reduced application of disruptive insecticides), beneficial arthropods were perceived to effectively suppress these pest densities (Murray & Mensah 1996), and beneficial arthropod densities were thought to decline from January onwards, regardless of possible food supplement treatments (Mensah 2002a, b; but see Scholz et al. 2002). There is scope to extend the 'application window' of supplements to include a wider range of pest species over the entire season. This opportunity is the consequence of improved development and increased adoption of IPM programmes for cotton (Wilson 2002). It is imperative that proposed changes to the nature of artificial food supplement programmes are economically feasible. In this study we assessed the effectiveness of applying multiple treatments of an artificial food supplement (Amino-Feed UV') during the growing season to enhance beneficial arthropod densities. We measured beneficial and pest arthropod abundance, mortality rates of sentinel heliothis egos, fruit counts, crop yield and fibre quality.