Signaling Science: What Household Solutions Repel Ants?

NO PICNIC: You can keep ant antics from ruining lunch using simple solutions made with ingredients from your kitchen. Image: George Retseck

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Key concepts
Biology
Chemistry
Chemical signals
Entomology
Repellents

Introduction
Have you ever had ants ruin your picnic? Commercial ant repellents can keep them away, but who wants to spray poison near their food? In this activity, you can investigate the effectiveness of some less toxic solutions that you may have around your home. Armed with your discoveries, you may be able to keep your next picnic from turning into an ant buffet!

Background
All animals sense chemical signals in their environments. Some animals use these signals to communicate. One animal famous for chemical communication is the ant. When you see a line of ants, it is because they are following an invisible chemical trail. This type of chemical signal is positive?it is called an attractant because it is meant to attract others. But signals can also be negative, warning other ants to stay away. This type of signal is called a repellent.

Sometimes repellents can come in handy. We don't like ants to get into our homes, so if we apply a negative chemical signal around their foundations, the signal will tell the ants to keep out. Chemical companies will sometimes try to copy a negative signal to sell as an insect repellent. But sometimes these chemicals can have side effects or be poisonous to pets or small children. Luckily, there may be less toxic remedies around your home.

Materials
???? Q-tips
???? Small cups or bottle caps
???? Large, vinyl tablecloth
???? A location outside where there are plenty of ants crawling around
???? Water
???? Sugar
???? Baking soda
???? Vinegar
???? Detergent (dish soap, laundry detergent, hand soap, etcetera)
???? Tabasco sauce
???? Lemon juice (or other citrus juice)
???? Commercial ant repellent, if you want to compare its effectiveness
???? Any other solution you would like to test!
???? Watch or stopwatch (optional)

Preparation
???? In a small cup or bottle cap, make a saturated solution by dissolving some baking soda into water. Keep adding and mixing baking soda until no more will dissolve.
???? In a small cup or bottle cap, make sugar water by dissolving sugar in water until no more sugar will dissolve.
???? If you use a commercial ant repellent, you should have adult permission and supervision.
???? Separately make up additional small cups or bottle caps of the solutions you will be testing: Water, vinegar, detergent, Tabasco sauce, lemon juice and, if you choose to test it, commercial ant repellent.

Procedure
???? Lay out your vinyl tablecloth on the ground in an area of heavy ant activity. Wait awhile for the ants to walk on the tablecloth. (Be careful when working with ants?some can sting and bite!)
???? Tip: If not many ants are walking on the tablecloth, you could try putting a small piece of fruit near them, such as an apple slice, wait until the ants cover it, and then carefully shake them off onto the tablecloth. If it is very hot outside, you may need to wait until later in the day when it cools down for ants to come out of their holes.
???? Next to the tablecloth have ready the solutions you will test: saturated baking soda solution, sugar water, water, vinegar, detergent, Tabasco sauce, lemon juice and, if you want, chemical ant repellent.
???? Test a solution on an ant by dipping a Q-tip into the solution and drawing a circle around the insect, about 2.5 centimeters in diameter. Did the ant stay inside the circle or leave it? Was there anything else you observed about the ant's behavior?
???? In this way, test solutions on the ants until you have tested at least five ants with each substance.
???? Which solutions usually kept ants inside the circle? From which did the ants readily walk out? Potential repellents will be solutions that clearly trap the ants inside a circle.
???? Were there circles in which the ants spent time standing, neither quickly leaving nor appearing trapped?
???? Extra: Once you find some potential repellents, you can figure out which ones work best. Try this activity again, but now time how long the ant remains trapped in the circle. Which repellents repel the ants for the longest amount of time?
???? Extra: You can also time how long the ant stays trapped in the circle to experiment with different concentrations of repellents. How diluted can your solutions be and still act as effective ant repellents?
???? Extra: Try a similar activity to this one but only test dry or powdered substances. You won't need a tablecloth for this; rather for a hard, dry substance like chalk you can draw the circle on a sidewalk. For a powder, like baking soda, sugar or salt, just sprinkle it in a circle around the ant. Can you find some powdered or solid substances that work as ant repellents?

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