Drug Bugs
The 2060s were a messed-up time, man. It took a while for the basic techniques for fast genetic engineering to make its way down to the high school level, but once it did — hoo, boy. Mix smart adolescents with the building blocks for Abominations of Science, and all sorts of stupid ideas can be born.
Like Drug Bugs! This species started out as an unholy mix of Hercules and Japanese beetles; Drug Bugs have the size (about 4 inches long) and wings of the former, and the diet and wider ecological range of the latter. This would not normally make them that much of a problem, as it’s easier to control bugs that size, but there’s an extra problem; the original brilliant teenaged idiot who put the Bugs together gave them an internal biology that produced THC as a waste byproduct. Only in trace amounts — originally — but the first Drug Bugs were designed specifically to confuse ranged chemical surveillance equipment, which were admittedly being extensively (some might even say ‘overly’) used by law enforcement at the time. The idea was to produce an environment where a positive result from using remote equipment like this could be later challenged in a court of law, and that was pretty much what happened.
But by then, of course, organized crime had gotten hold of the critters. The Mob’s own tame bioengineers first boosted the Drug Bug’s biochemistry to produce useful levels of THC; once they had an idea of the design architecture, the gene hackers then spread out their focus to make variant Drug Bugs that could produce cocaine, heroin, methamphetamine, and there were rumors that at least one dark lab had produced an LSD Drug Bug before various national governments descended upon the production network like a terrified tsunami. This, of course, virtually guaranteed that modified Drug Bugs escaped into the wilds; and we all know what happens when a genetically modified true-breeding animal enters a compatible ecosystem where nobody’s trying to eat it, right?
Fortunately, second-generation Drug Bugs were less robust than first-generation ones, leading to some quick applied natural selection; unfortunately, third and later generation Drug Bugs still produce measurable amounts of various illegal drugs in their excrement. Every drug agency on the planet hates Drug Bugs with a passion, and the ecological groups aren’t much friendlier. Possession of one is usually seen as prima facie evidence of possession with intent to sell whatever drug the Drug Bug produces, and most people seem to be OK with that.
On the other hand, in places where marijuana is legal Drug Bugs that produce THC are generally also legal to own, albeit with a permit. They make for fairly placid pets; people who keep beetles report that Drug Bugs live longer than you’d expect, and are extremely low maintenance. And that, contrary to popular belief, you can’t tell what drug the Drug Bug excretes from its appearance and behavior. That feature was apparently going to be in the next iteration of Drug Bugs, along with a mechanism for secreting the drugs more uniformly. Good thing none of them survived to escape into the wild, huh?