Get him his own magnifying glass.
You can also find small plastic collecting jars with a lens built into the top for observing the contents.
Using a babyfood jar, and plastic tubing, and the toe of a women's stocking you can make a great bug catcher.
As he gets older, spend your family TV time watching something worthwhile. My kids grew up watching "Uncle Dave" (David Attenborough) nature videos rather than reality/Disney/stupid TV. They're mostly on NetFlix. Seemed to work, eldest is studying conservation biology at the University of Montana.