Colour discrimination by the sheep blowfly Lucilia sericata

In laboratory trials designed to examine the alighting response of the blowfly Lucilia sericata Meigen to colour, yellow sticky cloth targets caught the largest number of both males and females, followed by pale blue, black, green, dark blue and red. The number caught by any colour showed a strong positive relationship with the percentage of its spectral reflectivity in the 450-580 nm wavelength band. In field trials, targets baited with the synthetic attractant "swormlure' caught significantly fewer L.sericata than targets baited with liver and sodium sulphide, suggesting that the former bait is a relatively poor attractant for this species, at the release rates used in the present study. However, there was no effect of target colour on catch, neither was there any interaction between colour and odour bait type. The results, from both the laboratory and field trials, suggest that the strength of responses by L.sericata to visual cues are weak relative to responses to odour. Responses to hue are readily overridden by a range of factors such as brightness and contrast with the background and are therefore likely to be difficult to detect or manipulate reliably in trapping systems in the field.