The Ibn Ezra (Shemos 9:1) noted that the plagues of blood and frogs were mediated through the medium of water, of lice and wild animals through the medium of soil, and of pestilence and boils through the medium
of the atmosphere. Plagues 4, 5, and 6, or, those afflictions caused
by swarms of wild animals, microbial pestilence, and skin boils,
are the subjects of this article.
Babich, H. (2010-2011). Plagues 4 to 6: Wild animals, pestilence, and boils. Derech HaTeva, 15, 66-70.
*This is constructed from limited available data and may be imprecise.