Table 3. Correlation between MMS levels and the mean numbers of mites collected from 27 corrugated cardboard traps in 37 caged-layer poultry houses.

MMS level	Number of farms	The average numbers of mites collected using 27 corrugated cardboard traps in caged-layer poultry house
		Mean ± SEM*	Minimum	Maximum
0	20	0.18 ± 0.04a	0	1.41 ± 0.50
I	5	68.64 ± 8.71a	2.22 ± 0.55	122.56 ± 30.83
II	4	293.62 ± 39.10b	205.96 ± 51.47	370.63 ± 132.36
III	4	415.23 ± 49.58c	379.85 ± 119.60	451.44 ± 82.75
IV	4	923.94 ± 121.15d	503.93 ± 66.54	1,909.96 ± 392.12

MMS, mite monitoring score.

^*Means followed by the same superscript are not significantly different at the 5% level of significance (Duncan test).