Gardens of the Cross Timbers: Freedom is not free
Happy Fourth! Tonight, PBS is hosting “A Capitol Fourth.” Watch the fireworks on TV as they go off above the National Mall in Washington D.C.
Still taste the grit between your teeth? A little bit of Africa landed in Oklahoma last weekend, covered the landscape with a light beige fog and turned the sky chalky bluish-white. The Saharan Desert dust is a little thicker this year. The annual SAL (Saharan Air Layer) forms every mid-June 5,000 to 15,000 feet (according to NASA, this year’s top is 16,500 feet) above the earth. The dust layer can be one to three miles thick and flows in westerly waves every three to five days over oceans and lands until mid-August. As the wind blows the dust around islands, mountains and other land features, it begins to rotate in the opposite direction, forming eddies and swirls as the dust sweeps to the west. Millions of tons of fine earth are sent thousands of feet into the atmosphere. The dust cloud is formed of sand, phosphorus as well as other minerals. As it travels the soil fertilizes the Amazon rainforest and enriches the North Atlantic Ocean to help feed ocean life.
What begins this process? The Sahara Desert in northern Africa is very dry and hot. Summer temps go over 117 degrees. The region experiences less than 4 inches of rain in a good year. Many years may pass between rains.
To the south of the Sahara is the Gulf of Guinea, much damper and cooler due to its location close to the equator. This area receives from 36 to 78 inches of rainfall every year. The extreme difference between the land mass and gulf water sets up wind circulations that actually scrub the desert floor as the sands are lofted upward and carried in the westerly winds. Oddly, SAL looks like a hurricane, but being much drier and hotter, sucks the energy that feeds hurricanes in the Atlantic. Thus, the hurricane threat is diminished as the periodic surges of SAL cross the Atlantic and Gulf of Mexico. As Africa begins to cool in August, SAL goes away.
On the other hand, the bagworms are settling in to stay. The junipers are in the battle zone. The redcedars (Juniperus virginiana) have some bagworms, but the four expansive junipers that form the backbone of dense shrubbery behind the birdfeeders and the two guardians in the front are being ravaged. The 30-year-old shrubs, some over 6 feet tall and 8 feet wide, have not enjoyed the past few Oklahoma summers. One died this year and another is on the way. The sandy soil on a slope has not helped. The soil in front of the house has a pH over 8.5. This was the staging area used when mixing concrete and grout during construction of the house. One Juniper is struggling.
What caused the explosive population of Thyridopteryx ephemeraeformis, the common bagworm? Erratic rainfall perhaps? I looked at the precipitation levels throughout the growth months. The moisture fell in spits and gully-washers.
My data reported to CoCoRaHS:
Temperature? Our winters have been too mild with little snow. In a 2016 report by the National Park Service, three quarters of parks noted the onset of very early springs. In 2020, many southern states reported spring arrived three weeks early. This affects the cycles of all other wildlife. It appears the bagworm eggs are hatching over a longer period of time. Various sizes and more of them.
The evergreen bagworm caterpillar cleverly cloaks itself in a small pyramid of leaves or needles, attaching itself to a branch using silk threads. Silk lines are used as bungee cords to drop the short thick prickly greenish icicles down to buffets on other stems. When time comes to form a cocoon in August, the mature larva spins silk around the branch, but this time to anchor the casing in place. This unassuming thread is so strong it can girdle the growing branch years after the moth is long gone.
Bagworms are so well camouflaged. You have to stand and stare at the branch for a minute or two to detect movement. Downright daunting to see nearly all the branches doing the bagworm dance. After spending hours picking off the little wriggling cones, a memory surfaced.
One year my dad decided to grow potatoes. We’re not talking a small patch, but a sizeable part of his garden dedicated to tubers. My sister and I were assigned the task of picking off potato bugs. We were issued Folgers coffee cans for the larvae and beetles. Doing this while standing in leafy plants nearly as tall as I was almost turned me off of gardening. As I recall, that was the year the rest of the garden became corn and tomatoes. One particularly vicious storm raked our little area of southeast Oklahoma and laid flat all the corn. The potato and tomato plants all leaned precariously at the same angle. Setting the plants upright in wet, mucky soil was frustrating. Many had opted to become ground cover.
Bagworms prefer isolated vulnerable junipers but can feed on 50 evergreen and deciduous plant families. But wait. The beneficial ichneumonid parasitic wasps feed on the caterpillars. It helps to first plant the flowers with shallow open blooms that attract these wasps. Cilantro and members of the dill family, carrots and cabbages work. The ichneumonids are tiny wasps that don’t sting. Great insects to have in any garden.
My Carolina wrens are having a field day with the caterpillars. Sparrows also find them tasty. The turkey family and squirrels could care less. The large ants will torment the caterpillars who are trying to get away on the ground, dragging their little needle cone home behind them. Too late to use biological sprays such as Bacillus thuringiensis (BT), but I wouldn’t do it anyway since it has been windy and BT kills all caterpillars (Monarch, swallowtail, etc). My one recourse is hand-picking. I know bagworms are easily drowned in soapy water, but I can’t do that. The lively little guys are weirdly fascinating and part of the natural cycle. Each morning I carry my container full of wriggling caterpillars to the nearby manicured Bermuda grass lawn and fling them to the heavens. Maybe they’ll develop a taste for Bermuda!
As the bagworms soon found out, freedom is not free. The 56 lawyers, jurists, merchants and farmers who signed the Declaration of Independence knew this. Five were captured by the British as traitors, tortured and killed. Twelve had their homes ransacked and burned. Nine fought and died as a result of the Revolutionary War. Many died penniless and in poverty.
“The advancement and diffusion of knowledge is the only guardian of true liberty.” James Madison
Becky Emerson Carlberg, graduate of Oklahoma State (Plant Pathology) is a teacher, artist, writer as well as certified Oklahoma Master Gardener and Master Naturalist. Contact her at Becscience@att.net.