cows have insects. one could collect all the various flies on the bovine, on the bovines pooh(flies are very pretty in a display. interesting insects out here in CA are praying mantis, lady bugs, tarantula hawks, various butterflies that migrate including but not limited to monarch's, giant water bugs, hemiptera's (half-wings), lace wings, tarantula's (try and find a male, they get eaten after the mate), various moths, . get a page viewing magnifying glass. insects are totally awewsome. there are special pins to display bugs. one could sort the display into genus, pest, non pest etc. one thing to do if you want to capture butterflies or insects with delicate wings, is to get a kill jar that has a very rapid death, but be careful to not breath it. a good source for bugs is the water, even in the mud. you can make your own nets for that with a decent heavy duty seive surrounded by canvas on the sides but not on the bottom. there are supply houses that deal in this stuff. great learning tool on how species are categorized.
one could include parasitic wasps in the collection too, and put the wasp next to what it preys on by placing it's babies strategically.
also forgot about velvet ants, there is orange, yellow red others. they are not ants, but wingless wasps.
http://www.whatsthatbug.com/velvet_ants.html