So how realistic is any of this? It’s hardly plucked from thin air.

University of Wyoming professor Jeffrey Lockwood wrote a book about entomological warfare, “Six-Legged Soldiers: Using Insects as Weapons of War,” and he weighed in on where the story line might have come from.

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The U.S. was indeed accused of entomological warfare during the Cold War — but not by Russia.

“There were a number of accusations made by the Cubans that we had used insects to spread dengue fever and a whole bunch of crop pests,” Lockwood said. But the accusations, which were mainly lobbed during the 1960s every time Cuba had an issue with its crops, were never proved.

North Korea and China also accused the U.S. of spreading germs using flies and mosquitoes during the Korean conflict, but no documents ever turned up to support the claim.

And decades later, in 1996, Russia filed charges on Cuba’s behalf — Cuba wasn’t a signatory to the Biological Weapons Convention, which is why Russia got involved — and a committee investigated. But it couldn’t confirm nor deny the charges.

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The truth is entomological warfare is pretty difficult to prove.

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“You don’t really notice the infestation until it’s well underway,” Lockwood said. “Distinguishing accident from intention, especially with something like a crop pest, is darn near impossible.”

Speaking of crop pests, the U.S. was on the receiving end of an infestation in 1986, but no foul play was proved. Russian wheat aphids did considerable economic damage, though the bugs were apparently imported accidentally along with the wheat.

So those are some events that most closely align with this season’s Russia-vs.-America story arc on “The Americans.” But the United States’ history of entomological warfare since the 1950s is fascinating in general, especially considering the country started out as an underdog.

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During World War II, the United States lagged behind Japan, which was a powerhouse in the field, in part because it wasn’t above experimenting on humans. The Japanese army killed hundreds of thousands of Chinese by dropping bombs that unleashed cholera-infected flies on the population, and the mastermind was Japanese surgeon general Shiro Ishii. He managed to avoid being charged with war crimes by agreeing to divulge his research to the American government. And just like that, the U.S. caught up to its former enemy.

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In the years that followed, the U.S. conducted insect research at Fort Detrick, and developed powerful weapons, including yellow fever-carrying mosquitoes that could infect on a massive scale. (A test using noninfected mosquitoes was even conducted on American citizens.)

It could have been devastating, but the public wasn’t really concerned, preoccupied as it was with the threat of a nuclear attack.

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“We had the impression in the U.S. at that time that we had pretty much mastered disease-carrying insects,” Lockwood said. This was the era of DDT, when yellow fever and malaria had been eradicated in the States, and Lyme disease and Zika hadn’t yet become an issue.

Whether or not the United States government knew it, the Soviet Union wasn’t particularly invested in entomological warfare at the time. According to Lockwood, they were more interested in using aerosols to deliver pathogens.

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“The idea coming out of World War II into the ’50s was technology was going to master the day,” Lockwood said. “Using insects kind of seemed primitive compared to stainless steel vats filled with bacterial pathogens that you could load up in a bomb or spray out of an airplane.”

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Entomological warfare eventually fell out of fashion. Under the Biological Weapons Convention, signed in 1972, the U.S. is prohibited from developing those kinds of offensive weapons.

“But it doesn’t preclude small scale biological warfare or entomological warfare methods as a way of defending ourselves,” Lockwood said. “In other words, you have to figure out what the enemy is capable of in order to defend yourself. And that line between defensive research and offensive production is pretty blurry.”