TPP belongs to the psyllid family the Triozidae. The Triozidae can be readily distinguished from other psyllid families based on the pattern of branching of the main veins on the forewings.
In the Triozidae the first split in the basal vein (going from the insects' body) has three branches (trifurcate) whereas in other psyllid families it has two branches (bifurcate) (Fig. 2).
Also, note that the membrane of the TPP forewing is completely colourless and the cubital cell is short and compact.
As less than 1% of all psyllids caught on yellow sticky traps placed in Australian potato fields belong to the family Triozidae, looking at the wing venation is a quick and easy way of determining whether a specimen is TPP or not.
If you have a specimen that does have trifurcating wing venation, then it is necessary to proceed to the Step 2 to determine whether it is TPP or not. If your specimen has bifurcating wing veins, then there is no need to proceed any further with this key as it can be discounted as being TPP.
Fig. 2. Forewing of a typical Triozidae (top) and Psyllidae (bottom) showing differences in the branching of the basal vein (circled). Note: a clear wing membrane and a short, compact cubital cell is characteristic of the forewing of the tomato-potato psyllid (Bactericera cockerelli).