Trivia 089: An apple a day

Traveling around Washington State, you sometimes see big, imposing signs along the highway reading “ENTERING APPLE MAGGOT QUARANTINE AREA – DO NOT TRANSPORT HOMEGROWN TREE FRUIT BEYOND THIS POINT”. These signs demarcate the boundaries of the Apple Maggot Quarantine Area. This quarantine area was set up by the Washington State Department of Agriculture to help control the spread of the apple maggot. These fruit flies lay their eggs in apples, and the larvae (maggots) eat them once they hatch. Apple orchards are an important and famous industry in Washington, so controlling the spread of these insects is a high priority. The apple maggots themselves are not native to the west coast, but started being found in Oregon in 1979.

There are precious few stories of humans winning against invasive species. Usually by the time we realize there is a problem, it’s too late. The most important thing we can do is to prevent animals and plants from being transferred in the first place. This is why customs agents check for food being brought in luggage on international trips. Even if you are carrying something as harmless as a piece of fruit off the plane with you, that fruit may be carrying unwanted pests (charges were later dropped in this particular case). Any food items that get confiscated by customs must be destroyed. But the agents must be very strict, as missing something could result in a new species invading an area with no natural predators and spreading out of control.

However, there are a few instances where we can claim victory. Perhaps the most impressive was the United Kingdom’s triumph over termites. Termites are present on every continent (except Antarctica), and are extremely difficult to eradicate. Not only are they hardy insects, but a single queen can lay over 1,000 eggs in a day. Once established, they can chew through all sorts of plant material, from the lumber we use in our houses to the crops we grow. It is estimated that termites cause over $5 billion in property damage in the US each year.

In 1994, termites were spotted at a house in Devon, in southwestern England. Termites do not like the wet, clay-filled soil most of the UK sits on. However, Devon had drier, sandier soil. In 1998, the UK government set up the Termite Eradication Programme (TEP) to deal with these pests. This was the only known termite infestation in the UK, and the government wanted to stop them from spreading any further. However, termites are incredibly difficult to get rid of. The colonies build their nests deep underground, so simply burning or demolishing the buildings would do nothing to stop them. Worse, any methods taken to combat the termites would have to be done extremely carefully. Simply removing all the topsoil was not an option, both due to cost and the risk of spreading the infestation by transporting the soil.

Ultimately, the TEP used a special insecticide – hexaflumuron – which inhibits the growth of the larval termites. They used wooden bait stakes to get the insects to bring the chemical back to their nests. Much to the dismay of the homeowners, they were not allowed to simply demolish their houses, and nobody wanted to buy them. Finally, after over two decades (and several preemptive declarations of victory) the TEP announced in 2021 that there were “no signs of termites in a zone 100 metres long and 30 metres deep” around the area. However, they will likely still be keeping a close eye on things, as in 2009, the termites were spotted again after 8 years of absence. But this time, researchers are confident they are gone for good.

So the next time you see customs agents searching people’s bags at the airport, remember – they’re doing a vital job to help protect us against ecological disaster. So finish your fruit before you get off the plane.

If you know anyone who would like to receive these, please have them send an email to [email protected]. And if you are actually an apple maggot trying to circumvent quarantine, let me know and I can take you off the list.

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