Insecta is *still* not rigorously defined. (Or if it is, it was recent enough that I haven't heard about it.) Does that make it unscientific? Should I start calling spiders, scorpions, and centipedes "insects"?
Isn't defined as a subgroup of Hexapoda?
Hexapoda - Collembola + Pterygota Insecta - Archeognatha + Pterygota.
http://www.tolweb.org/Hexapoda/2528 http://www.tolweb.org/Insecta/8205
[]s,
Roberto Takata