We developed a new sugar response assay independent on the flies' locomotion and restraining their movements less than in a pipet tip. Flies were tethered to a hook glued between head and thorax and tested for their proboscis extension response to a serial dilution of sucrose after 20 h of starvation. The assay is quite sensitive, since we were able to record a difference in the response of fles starved for 14 h versus 21 h Damrau 2014, as in the T-maze assay Colomb 2009. Fed flies never responds to tarsi stimulation, in contrast to honeybees. tßhnM18 mutant flies lack OA and accumulate TA Monastirioti 1996. We starved female flies for 20 h and tested their response to sugar in our assay. tßhnM18 mutant flies responded almost 40% less than their control (called w+ because the mutant and the control lines have a wild type white gene, in contrast to the original mutant obtained after P element excision, Fig. 1A). The sum of all positive responses over the 7 sucrose presentations was significantly different (Wilcoxon rank sum test, p <0.05 Fig. 1B).