Though arthropod and arthropodology are grammatically not same; as a "tag" the both ( i.e. tag arthropod and tag arthropodology) the both will work same.
Now if someone do not use the arthropod tag for a non-insect arthropod, instead choose the wrong tag entomology (that should be used for insects, ie a subgroup of arthropod) only, the problem is not of the tag. It is the users' ignorance. (however the ignorance is no wrong... no-one of us is omniscient)
Though using the term "arthropodology" may be one solution (because along with entomology; another word ending with "logy" would declare "I am another logy; I am not exactly same as entomology"). But people can still do the same mistake, because entomology is a fairly common English word (even often appear in daily newspaper), and there could be peoples who have listen about "entomology deals with various bugs" but not familiar with difference of entomology (and insect) with arthropodology (and arthropods).
The best way to recover it; is whenever we found such wrongly-labelled question, where a non-insect arthropod has been labelled with entomology; we need to edit/ suggest-edit to replace the tag with arthropod, with a comment that why the edit has been done. (A sample as follows):
Entomology means the study about insects, a sub-group of arthropods only. Since the above question is about an arthropod but not an insect; a more general tag arthropod has been suggested.
Entomology means the study about [insects](https://en.wikipedia.org/wiki/Insect), a sub-group of [arthropods](https://en.wikipedia.org/wiki/Arthropod) only. Since the above question is about an arthropod but not an insect; a more general tag [tag:arthropod] has been suggested.
Once the users become aware about this problem (and also while browsing through collection of properly-labelled question people will become more aware about labelling correctly)