Sure enough, three of them were there already, loitering at the southeast corner of the Lincoln Memorial.
Professor Donald H. Messersmith leaned closer. A female was clinging to one fluted column, a second female was on another and a male was hanging out on a third. (Bug profs can tell the girls from the boys; it's all in the headgear.) It was the advance guard of Chironomus plumosus, a.k.a. the midge."They'll soon be numerous, abundant, on all the columns and the walls," said Messersmith, stepping back from the evidence Thursday evening.
And that's why, beginning Monday, the lights that bathe the Lincoln and Jefferson memorials at night won't be coming on at their regular times on many evenings, forcing tourists to wait about an hour longer for those shots of illuminated national heritage.
Leaving Lincoln and Jefferson in the dark is part of a six-week test to see if the National Park Service can outduel a tiny pest that has plagued it for years and is a large reason the memorials' white marble surfaces have become severely stained and coarse in places.
According to Messersmith, an entomologist at the University of Maryland and a Park Service consultant for the project, the problem is this:
As twilight deepens on spring evenings, midges - harmless, mosquito-like flying creatures - emerge from the Potomac River after wintering as larvae in the mud. They see the Lincoln and the Jefferson memorials, glowing nearby in night lights. They are seduced. They must have the monuments. By the millions, the midges head for the lights.
But, not being rocket scientists, many splatter themselves against the memorials. Confused, others lay eggs on the walls. They leave droppings on the walls. They die on the walls. Spiders come to eat the midges. The spiders spin webs in cracks in the mortar. And the spiders leave droppings, too. It goes on like this until midge season is over in the fall.
The result: slimed monuments.
It's really a mess," said Don Wadase, chief of the division of resource management for the Park Service's capital region. "In the morning, we have to sweep them (the midges). We get a pile like this, by this." His hands etched a mound a foot high.
To be sure, there are other culprits: Gypsy moths, wasps, other insects and, particularly inside the monuments, lots of birds. But midges are one of the worst antagonists, especially on the outside walls and pillars.
Walking the perimeter of the Lincoln Memorial Thursday, Messersmith pointed to numerous small streaks on the marble blocks: "All of these are leftover - probably from last year - midge egg masses."
The mess is bad enough, the Park Service says. But cleaning the mess makes matters worse, because each washing contributes to what two new studies say is worrisome degradation of the marble surfaces. "Adding more water increases the amount of wear," said Wadase.
To reduce the washing and wear, reduce the mess. To reduce the mess, reduce the spiders and midges. And to reduce the midges, said Messersmith, reduce the monuments' lights.
But only at dusk.
While some creatures are diurnal - meaning they are most active during daylight - and others are noctural, midges are crepuscular, meaning they are busiest when the light is in transition. At twilight, in other words.
If the memorials' night lighting is delayed until sometime past twilight, Messersmith said, the midges won't be lured from the Potomac during their active period. By the time the lights come on, all good midges will have retired for the evening.
To see if he's right, he has set up a test. On Mondays, Wednesdays and Fridays through May 30, the outside lights at both memorials will not come on until about an hour after sunset. This Monday, for example, they will not be turned on until 8:46 p.m. On Tuesdays, Thursdays and weekends, the lights will come on at their regular time, about 6 p.m., though they aren't noticed immediately at this time of year because the sun is still up.
On every night, the outside lights will be turned off at midnight, the regular time. And interior lights illuminating the statues of Lincoln and Jefferson will remain on throughout the test.
Accompanied by two University of Maryland students, Ian Stewart and John Rumbaugh, Messersmith will visit the monuments during twilight to count midges in areas he has marked off on the walls. He hopes to find there are far fewer midges on the nights when the lights are delayed.
But if the test finds the lighting makes no difference, there are other possible solutions, including changing the color of the outside lights or erecting lights down by the Potomac itself to divert the midges from their path toward the monuments.
One way or another, said Messersmith, the midges will lose.
"I think all of us feel we're on a mission," he said. "I think there's an element of patriotism."