I've never heard of honeydew as aphid, um, aphid what, spit? urine? Is it used to catch prey?
Urine is i guess the best term. (waste fluid is how i heard it..)

is it used to catch prey? no, in fact it make the aphids likely to be kept as prey! there are species of ants that herd aphids, and collect the honeydew, they ferment it, and use it as food... (right food, ferment sugar syrup, food!)

there are several different type aphids, --some are specific to one or two plants, some type will 'florish' where ever they are.. but most aphids excrete honeydew!

and honey dew will rapidly turn black with mold.