Author: Roberta (Page 526 of 561)

Bug of the Week: Cochineal Scale

Can you find the insect in these photos?

cochineal scale

cochineal scale

If you guess the white fuzzy, waxy stuff might be a clue, then congratulations. Believe it or not, the insect we are going to explore today has been the subject of greed, subterfuge and may have helped our forefathers defeat the British during the Revolutionary War. Not quite what you’d expect from a tiny insect that spends its life feeding on cactus pads hidden under some white fluff.

When the Spanish explorers first came to the New World they discovered the natives were wearing bright red garments. They were amazed, because no color like that could be found in Europe. The Mixtec people had been culturing a tiny insect, called the cochineal scale, as a way to produce a wondrous dye.

The cochineal scale insects live on the pads of certain prickly pear cacti. I’m not even sure how the early Mixtecs discovered the red body of the scale, because all you see on the surface is white fluff. Underneath is a small blob that looks like a pinkish seed. Within the body, the hemolymph is deep red. Although I doubt you can see it, there are few drops of this red where a bird or something has pulled the scale from out of the waxy covering in the left, center of the photographs. (Someday I hope to get some better photos, but this was at a public garden and I didn’t want to disturb nature. As usual, The Firefly Forest has a good photo if you want to see another example.) Somehow the Mixtecs found the cochineal scale, however, and they figured out how to process them into a red dye.

The Mixtecs farmed the insects with skill and care. They would plant cactus pads infested with the scales, weed the plants, build walls to keep animals away from the plants, and even shelter the plants during rain showers so the insects wouldn’t get washed away. Then they would carefully collect and dry the female scales to make the dye powder. It was a hugely labor intensive process. Not to mention that the cactus pads were covered with painful spines, which had to be avoided.

Many people in Europe wanted the dye and there was a limited supply. At first, only the very rich and powerful could wear it, like kings and queens, or the bishops and cardinals of the Roman Catholic Church. By the year 1600 cochineal dye was an extremely valuable export from Southern Mexico. Gold was the only export from the region worth more money. Dried insect bodies were worth more than silver!

The Spanish went to great lengths to keep the origin of the dye a secret. In fact, the results of their subterfuge can still be found on the Internet today. You can find websites that mention the “cochineal beetle.” In the past, people thought the secret insect might be a beetle and this misidentification has survived until today. See this webpage, for example. Scale insects are flat, legless and have sucking mouthparts. Beetles are rounded, have hard wings called elytra, prominent legs and chewing mouthparts. Cochineals are scales for sure. Oops. And by the way, the insects make the red coloring within their own bodies, they do not obtain it from the red fruit.

Eventually the dye was used to color the “redcoats” of the British army during the Revolutionary War. I have read that our soldiers were able to recognize and selectively fire upon the high-ranking soldiers, because only the elite got to wear the bright red cochineal-dyed uniforms. The foot soldiers uniforms were dyed with a cheaper dye that gave a duller color. Thus, the officers were easy to spot.

In the 1870’s, synthetic red dyes were developed and they began to replace cochineal for widespread use. Cochineal in the United States is now largely used as a food dye, found in such products as sausages, candies, and juices, as well as cosmetics. Check some of the ingredients of pink fruit drinks at your local grocery and look for the word “cochineal.” You may have been appreciating these wonderful insects when you drank juice and you didn’t even know it.

Weekend Science Fun: Growing Crystals

Growing crystals can be fun because crystals grow and change in amazing ways and they can be incredibly beautiful. At times growing crystals can be frustrating because it may demand unusual and potentially hazardous materials, because it can requires patience when the crystals take a long period of time to grow, and because there is no guarantee of success. In fact, I was inspired to look into growing crystals because someone else had difficulty growing sugar crystals and wanted to know why. Do give it a try, however, because often you can learn more about science from the projects that didn’t work out as you planned than from those that turn out picture perfect. And once you are successful, crystals are awesome!

What are crystals? A crystal is a solid material that has its atoms or molecules arranged in a regular, repeating pattern. This causes the crystal to be symmetrical, and leads to many fascinating geometric shapes. For example, some form cube shapes, like table salt. Others form hexagonal shapes, like six-sided snowflakes.

If you get a chance, look at table salt or a snowflake under a hand lens or microscope. To catch a snowflake, put your hand in a dark (black works best) sock or dark, plain-colored mitten and allow snowflakes to fall on it.

Here are some photographs of naturally occurring crystals. This is rock salt, sometimes used for making homemade ice cream.

rock salt

This is a geode. A geode comes from gas pockets that formed in magma when it cooled. The crystals can grow slowly within the protected pocket, reaching their full potential shape.

geode

Let’s try a few crystal-growing experiments. They will almost all require an adult’s help.

1.    Growing Salt Crystals -fairly easy
Gather:

  • Drinking glass or small, clear glass jar
  • Hot water (requires adult help)
  • Table salt and Tablespoon size measuring spoon
  • Nail
  • Pencil
  • String

Fill the glass or jar about ¾ way full. Start adding salt to the water one tablespoon at a time. Stir after each addition until the salt dissolves. Keep adding salt until a bit remains undissolved. This is a saturated solution.

Now, tie one end of the string around the nail and drop the nail into the solution suspended by the string. Lay the pencil across the top of the glass or jar and tie the other end of the string around it. The nail is a weight to keep the string straight in the water, supported by the pencil.
Now it is time to wait. Over the next few days the solution should dry and leave salt crystals on the string.

2. Grow Ice Crystals – a Snowy Day Project
Gather:

  • A drinking glass or clear jar
  • Enough snow or frost from the freezer compartment of the fridge to fill the glass half way
  • Table salt and Tablespoon size measuring spoon
  • Small test tube
  • Water

Fill the glass half way with snow or powdered frost. Press down to compress. Add one Tablespoon of table salt. Now fill the bottom of the test tube with one inch of water. Place the test tube into the snow mixture. The snow and salt should start to melt, and at the same time the water in the test tube should start to freeze into ice crystals. Add more salt to the snow and swirl a bit to mix if things aren’t progressing.

3.    Sugar -Rocky Candy Crystals – A bit more detailed

The person who had trouble with the sugar crystals tried using the same method as the salt crystals above. She added sugar to hot water until it was saturated and then let it dry on a string. Making a sugar syrup by boiling the sugar in the water, and seeding the string with some dry sugar crystals works better. See the instructions for making rock candy at  About. Com.

4. Almost everyone has tried or seen the crystal gardens that use laundry bluing and ammonia. Both these ingredients need to been handled with caution.

Gather:

  • 2 Tablespoons table salt
  • 2 Tablespoons laundry bluing (available in the laundry section, read the warnings on the label first)
  • 2 Tablespoons household ammonia (read the warnings on the label first)
  • 2 Tablespoons water
  • disposable aluminum dish
  • Food coloring (optional)

Check the bluing bottle, it may have a recipe for a crystal garden on the side which you could use, as well. Otherwise, simply mix the ingredients in a disposable aluminum container. In the video below a cardboard toilet tissue was placed upright in the dish. Note:  you will see that strips have been cut in the top of the roll. Those were actually supposed to go into the liquid to help wick up the solution. Obviously it worked quite well anyway.

You can also pour the liquid over pieces of coal or even bits of clean, dry sponge.

Growing Salt Crystal Garden Video

You can grow crystals from kits as well. This example is aluminum potassium sulfate crystals grown on a granite base.

crystal

If you grow a cool crystal, be sure to take a picture, load it on a blog or website and send me the link. I look forward to seeing them.

For more information, ideas and links visit the crystal projects for kids page at About.com.

You can also buy kits (check customer reviews, images are affiliate links to Amazon)

Smithsonian Crystal Growing Kit

Amethyst and Diamond Crystal Growing Kit

Crystal Growing Tree

 

Bug of the Week: Mud Dauber Wasp

Ever found a glob of mud stuck under the eaves or against the window sill of your home? This black and yellow beauty is an example of the type of wasp that probably put it there. This is a mud dauber wasp (Sceliphron).

mud dauber wasp

Notice her impossibly thin “waist.”

mud dauber wasp

Any idea what she is doing on this flower? No, she is not looking for nectar. Depending on the species, she was actually searching for caterpillars or grasshoppers, which she feeds to her young.

The adult wasp catches and stings the insects she uses as food. Then she carries them to her mud nest, where she stuffs them inside a mud tube she has created. She lays an egg on the processed prey. Then she carefully covers up the open end with more mud. Her offspring hatch from the egg inside the tube, and consume the insect or insects she has provided for them. After the larvae finish development and become adult wasps, they chew their way out and to fly off to make more mud nests.

Whenever I see a mud dauber wasp, I always think of the poignant poem called “The Digger Wasp” in Joyful Noise: Poems for Two Voices by Paul Fleischman, Eric Beddows (Illustrator). This wonderful set of poems about insects is written to be read by two people, although with practice one person easily manage it. Even the most apathetic, disinterested poetry non-fan will love these poems, because they are more like songs without music. In the poem I am referring to, the digger wasp mother provisions a nest for children she will never meet. Really makes you appreciate the hard work they are doing. That’s why I never destroy a mud dauber nest unless I know for certain it is empty.

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