Here's a repository of illustration I made. Feel free to use them (CC BY-SA 4.0)

Landscapes

A desertic landscape with plants on the foreground, and a building in the background
A minimalist landscape I used as background for a set of slides
A futuristic landscape

Insects

An ant cleaning its antenna
A semi-realistic spider I once saw in my dreams
An ant antenna
An ant seen from the top (Formicinae)
A bee nesting in a flower pot
An ant head seen from the front
A semi realistic ant. Quite cute
A very realistic ant front body (Lasius sp)
A representation of the buccal tractus of an ant
A full ant body from the side
A bunch of insect heads I made as logos. Feel free to ask what species they are if it matters to you
A ant from the size (Myrmica)
A rhino beetle
A bee in the sand
An Osmia bee
An set of ant pupae, variant degrees of smelliness
A cute semi-realistic beetle I drew. It's heart shaped
A queen ant (Lasius sp) seen from the side
An realistic drawing of an ant brain, with regions in different colors
A drawing showing the neuronal pathway of smelling in an ant
A damselfly
A semi-realistic representation of a wasp
A bunch of ants forming a path (Dolichoderus quadripunctatus)
A drawing of a biblically accurate rove beetle
An ant pupa, with a scanning electron microscope image of the silk at the surface
A termite a draw by hand and vectorized.

miscellaneous

A campfire
A bunch of plants
A milk bottle, with different milkable animal represented on it
A realistic representation of microbial cells
A schematic representation of microbial fermentation
A anarcho-ecology flag with microbial ferments in the center
A bunch of microbial insect pathogens
a minimalist represention of a fungal spore
An abstract representation of diversity
A semi-realistic representation of a DNA molecule