Table 2. Results of choice experiments (non-combined data).

		Total time spent in arm (mean ± s.e., in s)		Number of first visits		Average number of visits (mean ± s.e.)		Average visit duration (mean ± s.e., in s)
Exp	n	Stimulus odour 1	Stimulus odour 2	Stimulus odour 1	Stimulus odour 2	Stimulus odour 1	Stimulus odour 2	Stimulus odour 1	Stimulus odour 2
1	72	62.00±3.72	77.63±5.65	42	30	3.60±0.17	3.60±0.16	22.40±2.98	28.00±4.27
2	55	59.10±3.50	83.76±5.58	27	28	3.44±0.18	3.69±0.20	21.92±2.47	27.92±3.99
3	53	58.25±3.65	82.29±4.91	34	19	4.42±0.30	4.91±0.34	18.00±1.51	20.33±1.29
4	74	59.34±3.75	72.42±4.59	36	38	3.26±0.15	3.53±0.15	20.24±1.37	23.90±1.98
5	64	70.70±4.68	85.40±4.64	33	31	4.05±0.22	4.25±0.24	21.67±1.34	26.50±2.50
6	61	53.33±3.20	75.08±4.32	30	31	3.39±0.18	3.80±0.19	14.05±0.59	22.00±1.32
7	93	63.39±3.30	73.05±3.35	54	39	4.62±0.24	4.38±0.16	17.55±0.86	22.55±1.47
8	97	70.29±2.89	76.34±4.33	47	50	4.76±0.18	4.62±0.17	16.59±0.77	25.61±3.34

For each experiment, the total time, the numbers of first visits, the average numbers of visits, and the average durations per visit of test cockroaches in each olfactometer arm are showed. Exp. 1–7: stimulus odour 1 = food plus non-feeding conspecifics (F+C), stimulus odour 2 = feeding conspecifics (FC); exp. 8: stimulus odour 1 = fresh food (F), stimulus odour 2 = recently consumed food (NF); n: number of successful tests (tests during which the cockroach visited both olfactometer arms). Statistical analyses performed on combined data are showed in Fig. 2.