Mosquitoes and Housefly are grouped under the phylum Arthropoda because they both posses jointed legs (or appendages).
Animals that have jointed appendages are called Arthropods (i.e animals with jointed legs). They are triploblastic (i.e they have 3 germ layers) and exhibit bilateral symmetry. They are both six-legged arthropods sub-grouped under the class Hexapoda (coined from the word "hexa" meaning six and "Poda" meaning leg). Their body are divided into three parts; head, thorax and abdomen.
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