I have a phobia of certain arthropods, especially of big ones that fly. Hornets and bumblebees are the worst. Dragonflies aren't easy too, but at least they rarely fly inside a room. Somehow the fear is connected to the label insect, so after I learned that spiders are not insects, my aversion to them has weakened (but not disappeared completely). I could rate arthropods on a scale measuring my fear:

1. Crustaceans (except woodlice): no problem at all, I can eat them.
2. Anything smaller than 5 mm in length (other dimensions play a role too, the smaller the better): I can touch or crush them.
3. Woodlice, centipedes, silverfish, harvestmen, smaller butterflies, caterpillars, ants, small beetles: can touch them, but crushing them makes me feel uneasy. Perhaps scorpions belong to this class.
4. Most spiders, flies, moths, big butterflies, big beetles, solifugae, true bugs: I try to avoid touching them at all.
5. Wasps, bees, dragonflies, cicadas, anything else which is big, flying, noisy or hairy: when one is near, I can't concentrate on doing anything. Being closed in a room together with few such beasts and no weapon (like a newspaper) is a nightmare.