Mystery solved!

Purple triangular boxes are popping up on trees all over the county. So what are they? Bird houses? Snake catchers? Summer decorations gone awry? Actually, they're bug detectors.
The Virginia Department of Agriculture and Consumer Services (VDACS), in cooperation with the United States Department of Agriculture and Fairfax County, is performing a statewide survey to determine the extent of areas infested with the Emerald Ash Borer (EAB).
According to the Department of Conservation, an EAB is a small, non-native beetle first noticed in the United States in Michigan in 2002. A native of Asia, the beetle's larvae kill ash trees by feeding on the inner bark and disrupting the tree's ability to transport water and nutrients.
The VDACS estimates that the beetle was accidently introduced to the United States through wood packing materials coming from Asia. Since it was first discovered in Michigan in 2002, the beetle has killed at least 20 million ash trees in Michigan, Ohio and Indiana. It was first detected in Virginia back in 2003 at an elementary school in Fairfax County. Unknowingly, infected ash trees that were sent from a nursery in Michigan had been planted at the school. To prevent the beetle's spread, all ash trees within a half-mile radius were cut down and chipped.
Since then, ongoing surveys have been conducted to detect the beetle and they usually turned up negative, until 2008. According to the VDACS, the beetles were detected again at multiple sites in Fairfax County, resulting in the issuance of a quarantine for the counties of Arlington, Fairfax, Fauquier, Loudoun and Prince William, plus the cities of Alexandria, Fairfax City, Falls Church, Manassas and Manassas Park.
"The quarantine means that you can't move regulated articles outside of those areas," Elaine Lidholm, director of the VDACS Office of Communication, said. "This especially means firewood. EABs can get under bark and you can't see them."
Other regulated articles include ash trees, green (non-heat treated) ash lumber and other ash wood products.
State agencies and the United States Forestry Service etimate that as of mid-2007, 287 ash trees have been destroyed by EABs but billions are at risk. In an effort to eradicate the pests, infected trees are removed and burned.
According to VDACS Commissioner Todd. P Haymore, the EAB problem is one that is not only harmful for the trees, but also for those that relay on them for sustenance.
"EAB has already killed millions of ash trees in Michigan, Indiana, Illinois and Ohio and we are aware of several infestations in Northern Virginia," he said. "The damage caused by this invasive insect can mean the loss of millions of dollars for homeowners, landowners, nursery and forest products industries.
It is extremely important to track the progression of EAB in order to alert localities to its possible spread which will help in making management decisions. If we can determine its spread, it will help unaffected localities develop options for the management of this destructive pest."
According to Lindholm, the purple boxes are a way for the VDACS to insure that the EAB problem hasn't spread to other areas of Virginia, including Orange County.
The boxes seen here are part of 3,500 detection boxes being placed all over the state. They are purple in color because, according to Lindholm, previous research has indicated violet colors are generally attractive to beetles in the family Buprestidae to which EAB belongs. They are also baited with natural plant oils to attract the beetles and a non-toxic glue to trap them once they are lured in.
"Unless we do this, it will be too late for the trees," Lindholm said.
She said that VDACS staff will periodically check the boxes for specimens and will remove them once the survey is complete. She also said that the traps are designed so that no birds or other wildlife will be harmed, however occasionally bugs that just happen to fly by, like beetles, flies and wasps, can get caught on them.
The survey program first began in April and Lindholm estimates that it will take until August to place all of the traps.
For more information on the program, or the Emerald Ash Borer visit www.emeraldashborer.info or call 804-786-3515.