National Geographic News
Bed bugs on fabric.

A microscopic image of two bedbugs on fabric.

Image from Eye of Science/Science Source

Ed Yong

for National Geographic

Published August 9, 2013

Fill an old coffee cup with ten tablespoons (150 grams) of sugar, two tablespoons (30 grams) of yeast, and one and a half quarts (one and a half liters) of water, and put it in the middle of an upturned dog bowl.

Voila! You have just made a bedbug detector that beats others on the market and is much cheaper.

This do-it-yourself (DIY) device to trap bedbugs was created by Narinderpal Singh, Changlu Wang, and Richard Cooper from Rutgers University in New Jersey. It does not kill the bugs, but it can alert homeowners to infestations at their earliest stages, when the bugs are more easily exterminated.

"This is about early detection. When you detect the bugs, then you can call the professionals," says Singh, whose study was published in the Journal of Economic Entomology.

Bedbugs are blood-sucking insects that have been feasting on humans for thousands of years. In the 1940s, they were mostly eradicated in the developed world using insecticides, but they are enjoying a resurgence that leaves tens of thousands of people with itchy welts.

Many scientists are racing to find new ways of dealing with the bugs, including synthetic bean leaves that impale their feet.

Detection Is Key

But spotting them is also a problem. The adult insects are about one-fifth of an inch (five millimeters) long, are mostly active at night, and hide in crevices during the day. This makes them very hard to spot by eye if there are just a few of them.

"By the time people see the bugs, they're already in their thousands," says Singh.

His new trap is just an upturned dog bowl from IKEA covered in surgical tape that has been dyed black. Bedbugs are attracted to black and have a natural tendency to scale vertical surfaces. Those that climb into the bowl have a hard time getting out.

The market's leading bedbug detector—the Climbup insect interceptor—is effectively the same, although its shallower sides are less effective at retaining trapped bedbugs. When Singh tested both designs in a tray and on the floor of an actual infested apartment, he found that the dog bowl captured three times as many bedbugs as the interceptor.

Irresistible Odor

The trap becomes even more effective when it is baited with a cocktail consisting of nonanal and 1-octen-3-ol (two substances found in human body odor), spearmint oil, and coriander Egyptian oil. As in a previous experiment, the team found that these four chemicals are good at attracting bedbugs.

However, sugar, yeast, and water work just as well. The yeast ferments the sugar to release carbon dioxide—the gas that bedbugs use to track down sleeping human hosts. This irresistible vapor lures insects toward the trap from long distances, and in experiments more than doubled the number that were captured.

Only one other monitor on the market actively lures bedbugs—and it costs between 40 and 50 dollars. By contrast, Singh says, "Our design is inexpensive, simple, and convenient. People can make their own after going to any grocery store."

Lois Topping
Lois Topping

I can't see how he got 1-1/2 quarts of water into a coffee cup.

Julie Leclair
Julie Leclair

i just want to know how long the trap is effective for? like after how many days should i replace it?

Danica Matovic
Danica Matovic

How long does it take for the bed bugs to get detected? I.e. how long do I need to leave the trap out to find even the smallest of infestations?

Roger That
Roger That

Your info was very helpful. The article mentions coating the inside of the dish with a resin, I assume to trap the bed bugs inside. is the purpose to make a sticky surface that they will get stuck to? Or a smooth surface that they can not climb out of with no traction? And what should a typical shopper use to achieve this? I did not recognize the substance they mentioned.

Andrew House
Andrew House

The paper was mostly concerned with creating a good bedbug lure, and less concerned with the actual trap. It concluded that a sugar-yeast- water mixture that produces 400 ml/hr of CO2 worked well in field ("real world") settings. Apparently people produce about 250 ml/hr, so you need more than that to lure the bugs away from the people and into the traps.

The recipe shown above was used in the lab setting and only produced an average of 100 ml/hr over four hours, so I'm a little confused why it was given here. Also a little suspicious of the grams-to-tablespoon conversion for the yeast. It's not the same as it is for sugar. My cookbook says dry yeast is 8.5g = 1 tbsp, so 30g would be 3.5 tbsp.

Anyways, the field recipe was 150g yeast and 750g sugar in 3 liters of warm water, which produced 400 ml/hr CO2. I'd use that recipe if I wanted to try it out in my bedroom. There was a 250ml (8 oz) coffee cup, but it was used to collect the CO2 as it came out of a compressed tank. Again, confused. The yeast-sugar-water mixture was kept in much larger vented plastic containers (a jug or a storage box), and simply rested on the upside-down dog dish(s). Check out figure 5b and/or 6a in the actual research paper.

Sleep tight!

Lisa Zizzy
Lisa Zizzy

Re: Joel

"They basically just stole my entire concept. I put this video together nearly 6 months ago"

Stole? Really?

It's not like bedbugs are a national epidemic or anything. You were most certainly the only one of the over 7 BILLION people on this planet smart enough to come up with this simple "concept", which is based on known bed bug behavior.

Yup, it's all about you. Thanks for gracing us with your presence.

dc boulder
dc boulder

This article should be simple but it is opaque. What is an "upturned" dog bowl? Was it too difficult to provide a photo of this mysterious device?

Barbara Landis
Barbara Landis

Great idea, but as addicted as I am to my caffeine, I don't own a coffee cup - new OR old - that holds over 48 ounces.

Forrest Snyder
Forrest Snyder

It was 1.5 liters, right? And I was thinking exactly the same thing. Why don't they give a recipe that'll work for 1 cup or 500 ml of liquid?

Dionne Cornwell
Dionne Cornwell

What if i can't find an old coffee mug that holds 1.5 quarts?



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