The Average Varroa chart shows the national monthly average varroa level based on all
samples
and all years in the APHIS survey, charted as a line. The error bars are based on
the 95%
confidence interval which represents the range that 95% of all samples are within.
The error bars for the sentinel site averages represent the minimum and maximum
varroa levels found. Months without columns have no samples taken during those
months.
The Average Nosema chart shows the national monthly average nosema level, compared to the
selected sentinel sites using the same methodology as the Average Varroa chart.