re: Lovebugs: do they serve any useful purpose to the planet?

Love bugs do not serve much purpose. They are a fly in the march fly family. They do recycle (eat) decayed vegetation in the larval stage, which creates organic matter in the soil, but do not eat much else (adult males live little more than 3 or 4 days, and definitely do not eat aphids). The species was NOT created in a lab, as the popular legend has, although they were not documented in the US until the early 1900s. There are actually 2 species of "love bug" (genus Plecia) in the US, although one is native to woodlands and not encountered as often. Plecia neartica is the one we most often see in the spring and fall.

Love bugs are more common along highways because of their attraction to gas and diesel fumes, especially in the middle of the day due ultraviolet light levels and temperature. The vibration of vehicles also contribute to this (same as the lawnmower example stated earlier). The reason those suckers tear up your car's paint job is because their body chemistry is slightly acidic, and becomes especially acidic (4.5 pH, for whatever reason) after their splattered body sits on your paint for a while.

Moral of the story...the bastards are probably more of a nuisance than any good they do. Earthworms are just as good at creating organic matter.

Maybe not... Can find no description of this import theory,so far

Never have read that, and definitely a new one for me. All I've ever heard is the "lab experiment gone wrong" explanation, but apparently they are like a biannual version of a cicada.