Bugs on Your Face

Out of all the things you could put on your face, bugs are probably not high on the list. There are much better things to feel–cotton balls, soft textiles, face creams and lotions, etc. Makeup is another common thing that goes on our faces, and most people wear some form of it at some point in their lifetimes.

Here's something you may not realize: if you've ever worn red lipstick or most blushes, you've had bugs on your face. Surprise! 

We got to demonstrate the power of natural
dyes ourselves at last week's Science on Main
event. These are ground-up cochineal bugs!
PC: Jessica Noviello.

Many natural products are used in makeup, and have been for years because of their bright colors. The specific bug used to make red, for example, is the cochineal bug (Dactylopius coccus), which are native to northern South America and into the American southwest region. The cochineal bugs are mostly immobile parasites that live on the undersides of prickly pear cacti pads, which means these bugs are technically an Arizona export product too, just like copper is. These bugs are scraped off of the cacti and eventually dry out in the aridity and high heat once removed from their homes. 

Once the bugs are dried, they are then ground up to extract a chemical called carminic acid (C22H20O13), which can make up as much as 25% of their total body weight. While they were alive, these bugs produce the carminic acid to deter predation ("don't eat me! I taste really, really nasty!"). Unfortunately tasting bad does nothing to deter humans who want to use the carminic acid to make things a beautiful bright red color. The carminic acid is then mixed with aluminum or calcium salts to create the compound carmine dye, also known as cochineal after the insects it came from, and is then used to make food and makeup a bright red shade. Next time you're looking at makeup or red food, look for the words "Natural Red 4" or "E120;" both are made from cochineal bugs.

We got to demonstrate the power of natural dyes ourselves at last week's Science on Main event. The picture above shows ground up cochineal bugs that we, the SoM Team, were using to demonstrate how colors are made. We first mixed the cochineal bugs with water, which has a neutral pH. pH is a chemical property that measures how acidic or basic a liquid is. Something with many H+, or hydrogen ions, is more acidic than something with more OH- ions. Something like water, which has equal amounts of H+ and OH- combined into H2O, has a neutral pH, right in the middle of the pH scale.

A visual pH scale. PC: https://neptunecoffee.com/is-coffee-acidic

The total range of the pH scale goes from 1 to 14. Things that have a pH lower than 7 is an acid, and things with a pH higher than 7 is a base. The farther away a number is from 7, the stronger the acid or the base is. Most things close to 7 are okay to eat, but things like bleach (pH = 13) or battery acid (pH = 1) are potentially deadly if swallowed. This is why you should never eat something in a chemical laboratory!

When we mixed the cochineal bugs with water, the mixture was a light red. When mixed with vinegar, a medium-strength acid, they turned more orange, and when the bugs were mixed with a base (sodium carbonate), they turned a beautiful purple. The cochineal bugs' shells were reacting with the different chemicals and creating different colors. This is one example, but there are thousands of these small chemical reactions that go into creating makeup, paints, foods, and all kinds of colorful things that humans use.

Take a look at your common household items. Are there any natural dyes there? Let us know!