Climate change has side effects
Posted: Tuesday, July 3, 2012 8:00 pm
By: By Jimmy Williams
“That which the palmer-worm hath left hath the locust eaten; and that which the locust hath left hath the canker-worm eaten; and that which the canker-worm hath left hath the caterpillar eaten.” Joel 1:4
To paraphrase: That which the bagworm hath left hath the Japanese beetle eaten; and that which the Japanese beetle hath left hath the spider mite eaten; and that which the spider mite hath left hath the leaf-roller eaten.”
Bugdust (as my friend George Smith used to say) on this here “climate change.” One of the supposed peripheral effects of the phenomenon is an overabundance of six- and eight-legged vermin. Do tell.
The worst infestation of bagworms in a long time has been reported here and across West Tennessee, and maybe beyond. Horror stories tell of whole evergreens seeming to move as thousands of immature bagworm caterpillars devour greenery at warp speed.
Horticulturist Jason Reeves of Jackson emailed a picture of a Morgan arborvitae there stripped to a skeleton.
The critters have attacked even some species that are seldom affected, among them bald cypresses and Japanese maples.
Bagworms are most familiarly noticed by their cocoons, made of pieces of leafage in their diet and thus cleverly camouflaged among branches. But plenty of damage can occur before they even build their homes, when the juveniles, appearing as small caterpillars, hatch by multitudes and go aspoiling.
Most insecticides, fortunately, easily undo them and, if they are caught in time, little damage results. The old favorite, Malathion, works, as does liquid Sevin.
What the bagworms have missed is subject to a more recent nemesis, Japanese beetles. They were virtually unknown here until a few years ago, and have migrated from the northeast into this area, having made their appearance there from Japan many years ago.
For all the world like miniature June bugs, Japanese beetles fly about until they see or smell victims, most commonly roses, crape myrtles and hibiscus. They then proceed to skeletonize the leaves thereof, generally causing little permanent damage but stunting plants as they are forced to leaf out again, always a weakening effort.
I said “generally.” In case of severe infestations on young plants, they can, on occasion, kill. I had a nice young Japanese climbing hydrangea assassinated by them a few years ago.
This year’s Japanese beetle numbers have (knock on wood) been less than they were a few years ago, when they descended by the thousands. They are harder to deal with than bagworms, partly because of sheer numbers and partly because they reproduce from underground grubs in waves. Kill a few hundred thousand one day and as many are back the next. Incidentally, the widely sold beetle traps work, but save your money to buy more plants. The traps draw in far more than they catch.
Even more problematic are spider mites and lace-bugs, both of which can decimate azaleas and some conifers overnight. The mites are microscopic but descend in millions, attaching to the underside of leafage and sucking sap. Mottled, whitish leaves are a giveaway. And, yes, they can kill a plant. A favorite is dwarf Alberta spruce. Once you see brown needles, the plant is usually gone.
One of Murphy’s laws has it that every time you find something that works they will quit making it. Such is the case with any chemical that is effective on spider mites. Insecticides are useless, since the mites are not insects but, instead, have eight legs, and, more importantly, are highly resistant to insecticides.
Cygon was my standby for years, and now it has been forced off the market by the greenies. There are newer miticides out, but I cannot testify as to their effectiveness. Look for a systemic miticide — that is, one that is absorbed into the plant structure and works from within. These are very effective indeed, and longlasting.
Canna leaf-rollers are small caterpillars that work from deep inside young canna leaves, before they expand. Upon opening, the leaves exhibit ragged holes that ruin the looks of the plant but do not kill it. The damage has been done, however. After all, the big paddle leaves of cannas are their chief attribute.
Systemics work on them, too. Applied to the ground at the plant’s base, or in the soil, they will take out the leaf-rollers before they do much mischief.
Editor’s note: Jimmy Williams is production superintendent at The Paris Post-Intelligencer, where he also writes this column.
Published in The Messenger 7.3.12
Jimmy Williams, The Garden Path