[pfdietz]

There are some potentially very nasty diseases spread by ticks and insects. For example, flaviviruses like West Nile, Dengue, and Powassan (which debilitated and ultimately killed the wife of Canadian fantasy author Charles de Lint.)

[BigTTYGothGF]

Arthropods of all (most) sorts: https://en.wikipedia.org/wiki/Arbovirus

[mr_toad]

Not to mention Malaria, which kills over half a million people a year.

[intrasight]

And has killed a large fraction of all humans who have ever lived.

[OutOfHere]

It has, but it also has saved a lot of people by slowing down invasions.