arms race

mosquitoes navigate by CO2
plus IR gradients to find their prey
which makes it hard to see what one could do
to keep blood-sucking parasites at bay
and vampire bats add sonar to the mix
of signals guiding them to their next meal
while no one seems to understand how ticks
make out unless they're doing it by feel
and who can understand a leech's mind
that eyeless, earless, gloms on in the creek
perchance vibrations guide their quest to find
the hemoglobin bounty that they seek
beset by such a fierce array of threats
a billion lives depend on sheer bed-nets