And you thought cicadas were just noisy and ugly.
Officials in Alexandria and Arlington said the unusual insects -- which popped up in the Washington area in May and June after 17 years underground -- provided a feast for the area's rodent population, which they say is considerably larger this year and the source of more residential complaints.
While there are no statistics to bolster the cicada-rat theory, officials point to anecdotal evidence culled from exterminators to suggest that the cicada invasion is at least partly responsible for fueling the area's rat population.
"It's logical," said Mike Conner, Alexandria's chief fire marshal, who oversees property maintenance for the city's code enforcement division. "Cicadas are laying on the ground and the rodents are going to eat them. It's going to cause greater proliferation. It's a food source."
Alexandria, a densely populated waterfront city, budgets $168,000 annually for rodent control, which includes measures such as baiting the city's sewers to stem the spread of rats.
Conner said several area exterminators have reported an increase in the rat population over the same time last year.
"They told us the cicadas were excellent feeding material for the rodents," Conner said. "I guess they're loaded with protein."
Rats have an average of three to six litters of six to 12 offspring per year. A female can produce up to 54 offspring a year.
In Arlington County, officials say the number of complaints they have received about rats in the last two months is dramatically larger than last year.
Last July, the county received 60 calls about rats. As of Friday, officials had logged 197 complaints for the month.
"That's four-fold higher," said Aftab Hussain, an environmental health specialist for the county who oversees insect- and rodent-borne diseases. "While there's no scientific data about [the impact] of cicadas, people believe the increase in the rat population is because of them."
University of Maryland entomologist Michael Raupp knows cicadas and isn't convinced they're the culprit.
"There's nothing in the literature that I've seen that links rats eating cicadas," Raupp said. Still, he said "rats are opportunistic eaters. If there were a bazillion cicadas, it could have been a significant food source."
Joseph Goodwin, manager of Alexandria Pest Services, said that based on calls for service, he believes the rat population is out of flux. The culprits, he says, were the cicadas.
"We're doing whole neighborhoods right now on Russell Road, in Old Town, in Springfield and Annandale," Goodwin said. "It's all of the areas hit hard by the cicadas. There was an increased food [source] for everything. All the litters were all increased. Now there's an influx of life."
Goodwin points to his company's recent sales of bait boxes. The company normally sells about 10 cases a week. Over the last two weeks, Goodwin said, they've sold 55 cases.
There are plenty of skeptics, however.
Robert Corrigan is an urban rodent specialist who helps cities around the globe solve their rat problems. As far as he is concerned, there is at best only a minor link between cicadas and growing rat populations.
"Everyone is looking for simple answers, but it's complex," Corrigan said. "It's urban sprawl. It's milder winters. It's increased demolitions. It's the public not paying what they should for very thorough pest-control programs."
Although he said the cicadas provided "one giant good meal" for the local rodent population, Corrigan insists "it's not going to explain the explosion of rats."
Richard Kramer is technical director for American Pest Management, which has a contract with the State Department to send experts to overseas embassies, where they train personnel in pest-control management. Kramer said rats are very territorial eaters and doubts they were very interested in the cicada smorgasbord.
"Does that mean they don't eat cicadas?" Kramer said. "No, they probably ate some, but I don't think that spike in activity would account for increased rat problems."
Whether you buy the cicada theory or not, officials agree that homeowners can take important steps to avoid rodent problems.
Keeping trash in receptacles and off the ground is an important first step. Firewood stored outside should also be kept elevated in a rack at least six inches off the ground to avoid rodent nesting.
Bird feed should never be scattered on the ground; officials say it should be provided to birds in feeders at least 36 inches off the ground.
Ivy, a shady habitat perfect for rodents to burrow in, is also a big no-no.
Alexandria requires homeowners who plan to disturb their property with construction to lay rodent bait seven days in advance. Officials note that construction around the new Woodrow Wilson Bridge has been a big problem, scattering displaced rats into Old Town's restaurant district, where restaurateurs have to be vigilant.
"Most people don't realize they may be the source of the problem," Conner said. "You plant lovely ivy, you leave your trash on the ground and you're spreading bird feed. Hey, surprise, it's you."