In our November post we covered three pests that can give gardeners winter headaches. Here are three more you’ll need to worry about.
Many thanks to Cyd Brown, Somervell County Master Gardener, for submitting these articles.
SCORPIONS (order Scorpiones)
Identification and Biology
You may never see scorpions in your garden. They are mostly nocturnal hiding under debris, rocks, and mulch. You may be able to spot Scorpions at night with a UV light,
Scorpions are predatory arachnids. They have four pairs of legs, two pincers or claws for holding prey, and a long tail tipped with a long stinger. The scorpion’s sting delivers a shot of neurotoxins which paralyzes its prey. Female scorpions can give birth about every two weeks and will carry their young on their back.
The most common species found in Texas is the striped bark scorpion.
Damage
Fortunately scorpions won’t damage your plants. Unfortunately, scorpions can deliver a very painful, and sometimes serious, sting if they are disturbed.
Contrary to common lore, most scorpion bites are considered non-lethal to humans. However, according to Web MD, venom from a bark scorpion can cause symptoms “like fast breaths, high blood pressure, a racing heart, weakness, and muscle twitches.If you think you’ve been stung, don’t take chances. Go to the nearest Emergency Room. Take the scorpion with you if you can (dropping the scorpion in boiling water will kill it.)
Management
You will likely only have problems with scorpions if you surprise them. Wearing good work gloves is the best defense. Scorpions love dark warm place – like shoes. To prevent toe stings, don’t leave shoes or boots in the garden or greenhouse.
Remove all unnecessary debris and mulch.
Natural oils can be effective short-term treatments for scorpions. These oils include; clove oil, rosemary oil, and cinnamon. Use synthetic pesticides like permethrins or carbaryl (Sevin) can deliver more long-term treatment.
Thrips (order Thysanoptera)
Identification and Biology
Thrips are tiny, almost microscopic pests measuring about 1/32” long. Females lay eggs in plant tissues. After hatching, thrip larvae drop off the plant to pupate in the soil. This development cycle can take between 8 and 20 days.
There are about 6500 known Thrip species. Some thrips feed on plants. Others are predators that hunt insects or other Thrips. Only a small number of Thrip species threaten plants.
Damage
Plant damage from Thrips can vary depending on Thrip specie. Like other insects, Thrips can cause damage during feeding creating silver or bronze colored leaf spots. Leaves will eventually fall prematurely. They can secrete honeydew which will attract ants and form black mold.
Perhaps the most serious problem caused by Thrips is the insects’ ability to spread plant viruses. These viruses include spotted wilt virus (tomatoes), nectrotic spot virus (impatiens), and Silver Mott Virus (melons and potatoes). NOTE: Thrips are the only known insects that can spread tospoviruses – diseases that can cause serious economic damage.
Monitoring
Thrips are attracted to yellows and blues, so yellow or blue sticky cards can be used to catch them. Blue or white water pan traps can also be used to detect them. To check for thrips, beat flowers or plant leaves above a piece of white paper and look for tiny walking dashes.
Be aware – Thrips can bite. Avoid wearing bright colors (especially yellows and blues) in the garden.
Control
Thrips can be very difficult to control as many species are known to have developed resistance to pesticides. Products with the active ingredient Spinosad is probably your best bet.
Many experts recommend proven sanitary gardening practices as an effective Thrip control. Remove infested plants from the garden or greenhouse as soon as possible. Cleanup debris such as old mulch and dead plants. Burn garden garbage if possible. Be careful not to create tiny shelters where Thrips can hide and multiply.
Scale Insects (infraorder Coccomorpha)
Identification and Biology
If you see what looks like tiny fish scales slowly moving around on your plants’ leave or stems, you may have a scale insect problem. The scales you see protect the underlying insect and cover the bug’s head and legs. Scale insects come in two flavors; soft and hard.
Soft scale insects have a leathery, waxy scale that stays attached to the body. These species feed on the plant’s vascular tissue (phloem) and will produce a sticky, ant-attracting honeydew. The hard scale variety has stiffer wax, and feeds directly on the plants’ cells.
Only immature scale insects move. At maturity the scales drop off and the insects become immobile.
Damage
Large infestations of scale insects can cause serious plant damage. Leaves may turn yellow or distorted and fall prematurely. Deposits of honey dew will attract ants (ants protect scale insects from predators) and will eventually begin growing mold.
Control
Heavily pruning infested plants is the best defense. For houseplants, wash leaves and stems with a soft toothbrush or cotton swab dipped in soapy water or isopropyl alcohol. Horticultural oil, insecticidal soap, or neem oil can also be used.
Be sure to remove honeydew spots and control ants.
In colder months, apply dormant oil to the woody plant parts. This will help control over wintering scale insects.