TPP can be distinguished from most other Australian Triozidae based on the number of spurs present on top part of the tibia of the hind-legs: TPP has one outer and two inner apical spurs (1+2) (Fig. 3) whereas most other Triozidae have none or a different arrangement of spurs (e.g. 1+3, 2+2 or more).
However, some species of Triozidae (e.g. T. adventicia) may have the same arrangement of tibial spurs as TPP.
If your specimen does, then it is necessary to look at a suite of diagnostic characters which distinguish TPP (proceed to Step 3).
If your specimen does not have this arrangement of apical spurs, then there is no need to proceed further with this key as it can be discounted as being TPP.
Fig. 3. Hind-leg of the tomato-potato psyllid (Bactericera cockerelli) showing the arrangement of apical spurs on the tibia.