Many flies of the family Tephritidae have stripes on their wings and black markings on their thorax which make them look like jumping spiders (Salticidae), especially when they display their wings horizontally. Previous studies have shown that salticid spiders respond to tephritids by displaying and retreating, arguing that tephritids evolved as mimics of salticids to protect them from predation by the latter. Here I show that the jumping spiders' reaction to a tephritid fly, the Mediterranean fruit fly (medfly) Ceratitis capitata, depends on the spider's size, age and sex. Large, adult female jumping spiders seem to be the least confused or intimidated by the medfly. This reduces the benefits that may derive from the resemblance of tephritids' wing and thorax patterns and displays to salticids, and leaves some doubt whether these flies' special characteristics solely evolved to confuse spiders.