Photograph by ILIK SACCHERI
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Researchers put caterpillars in boxes with sticks of different colors to test their “extraocular photoreception”—their ability to sense colors with more than the tissues of their eyes.
Photograph by ILIK SACCHERI

An insect’s surprising way of seeing, and other revelations

Research points to a greener way to make cement, a therapeutic use for magic mushrooms, and a caterpillar that sees colors with more than its eyes.

This story appears in the August 2020 issue of National Geographic magazine.

How can insects turn colors they can’t see?

Peppered moths are masters of camouflage. In the larval stage, they can change the color of their skin to blend into their settings—even without seeing those surroundings, a new study found. After raising more than 300 peppered moth larvae, U.K. researchers obscured the vision of some with black paint (which the larvae later shed, unharmed). The larvae were placed in boxes containing white, green, brown, or black sticks, and given time to adapt. When the researchers opened the boxes, they found that nearly all the caterpillars, with or without vision, had changed their body colors to match the sticks in their box. The researchers then moved the caterpillars into new boxes containing sticks of two different colors, and about 80 percent of the insects chose to rest on sticks that matched their body color. The researchers say their findings provide strong evidence that peppered moth larvae are capable of dermal photoreception—seeing with their skin. —Annie Roth

Cement of the future?

The process for making cement creates so much greenhouse gas that if it were a country, it’d be the third largest emitter on Earth. That statistic is from MIT, where scientists devised a process that would produce cement using electricity, rather than by burning fossil fuels. In a water electrolyzer, current to the electrodes creates hydrogen and oxygen gases, an acid, and a base. When limestone is added to the acid, it’s dissolved and decarbonated—loses its CO2—and then can be used to make a key cement ingredient. —AR

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Scientists at MIT have devised a way to use an electrolyzer to create cement without generating large amounts of greenhouse gases, as the traditional cement production process does.

To attract the ladies, a male moth flashes this

A male Creatonotos moth inflates his bushy behind only at mating time, and for one purpose: to lure females. The tubular organs are coated in bristles that emit pheromones. The more toxic plants the males eat as larvae, the bigger and more potent these organs will be. —Maya Wei-Haas

Medicinal uses are mushrooming

Patients in a pilot study felt decreased symptoms of anxiety and depression for at least one week after taking a large dose of psilocybin, the hallucinogen in magic mushrooms. The study findings, published in Scientific Reports, suggest that the drug may support an “enduring shift” away from negative moods and cravings. —Patricia Edmonds

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Psilocybin, the key ingredient in magic mushrooms, is being studied for use against depression and anxiety.