The blockage rates of X. skrjabini fed by Y. pestis spiked bloodmeal (1.0 × 1010 CFU/ml), and the flea numbers were shown in the brackets under the days post infection. A). Blockage status of fleas investigated daily. B). Cumulative percentages of blockages for the investigated fleas (for example, blocked percentage of day 5 p. i. was calculated by the total blocked fleas and total investigated fleas from day 1 to day 5 p. i.).