Each spring and summer we look forward to the ever-changing landscape. New colors and fragrances seem to show themselves on a weekly basis. The warmer and longer days of the seasons do not just usher in floral fireworks, they also influence insects to emerge and start their life cycle over again. Our recent winters have been fairly mild, allowing greater populations of insects to hatch, or emerge from larval form. There are literally millions of species of insects on Earth. Thankfully, we only have to worry about a handful in the landscape. This is a list of the five most popular insects that we are questioned about at Fairview.
1. Japanese Beetle
Oh, yes. The ever popular Japanese beetle. If you have lived east of the Mississippi and north of Florida, you have no doubt come into contact with these irritating critters. Japanese beetles damage landscapes as two forms. First, as grubs, the beetles devour the root systems of lawns. This feeding occurs in late summer to early fall, and again in early spring leaving a thinning, weak, and brown lawn. The adults emerge from the soil in early June and begin to wreak havoc in the landscape. Much like a teenager at a pizza buffet, Japanese beetles will devour most anything in its path. The beetles eat the leaf tissue between the veins of leaves, leaving a skeleton of the prior leaf. Flowers are not immune to the damage of the beetles. The plants most affected in my landscape last year were roses and crepe myrtles. These resilient pests removed many flowers before they were at their peak. There are two ways to treat and kill Japanese beetles in the landscape. Milky Spore is a naturally occurring bacterium that can be applied to lawns to kill the beetles in the grub stage of development. Milky Spore prevents damage to lawns by killing the grubs, and prevents damage to plants by reducing the number of adults each year. It takes anywhere from one to five years for the bacterium to be prevalent enough in the soil to fully function. Once established, the product can last from fifteen to twenty years without re-application. If beetles are already present, Milky Spore will not be effective and a spray must be used. Sevin is the spray used by many gardeners to control the adult form of the beetle. This year, I will spray my roses and crepe myrtle as soon as I see the first beetle to prevent damage to my plants. Japanese beetle bags have been used for many years to control the population of beetles. The bags use a pheromone as an attractant with an insecticide to kill the beetles once in the bag. The bags work as advertised. They attract and kill beetles. The negative is that they attract beetles. If these bags are used, it is highly recommend that they be placed as far away from prized plants as possible.
Many customers bring samples of plants to Fairview that are being attacked by aphids. Their presence in the garden is fairly common. Aphids damage plants by piercing plant tissues with their needle-like mouthparts (stylets), and suck the sugary substance out of the phloem of plants. They are typically found on the new growth or buds of plants where the tissue is softer and the nutrient rich liquid is easier to reach. Aphids can severely stunt and distort the new growth of a multitude of plants. A secondary issue that comes along with aphids is sooty mold. As the aphids eat, they excrete “honeydew” which falls onto the foliage below the insects. The honeydew is an ideal food source for the sooty mold fungus. Sooty mold is fairly common on crepe myrtles and gardenias. The fungus will cover leaves leaving them a charcoal color. A third issue, although not as common, is that due to their method of feeding, aphids can transmit viruses from one plant to another. Aphids are best controlled by Sevin, or a systemic insecticide. Bayer and Ortho both produce reliable systemic products that are applied to the root system of plants, and taken up by the vascular tissue of plants. From there, the products can work “from the inside, out”. Systemic products are good to use as preventatives against aphids and other types of insects. Lady Beetles actually eat aphids and are a good biological control.
Scale is a rather interesting insect. Scale produces a waxy “shield” over its body to protect itself from predators. This can make disposing of them very difficult. There are two methods recommended for scale removal. The first is using systemic insecticides. Scale feeds very much like aphids. They have the straw like mouth parts that allow them to pierce plant tissue and siphon out juices. By using systemic products, scale can be both prevented and controlled. Many topical sprays are not very effective in controlling scale populations. All Seasons Oil is the best product to use topically. This is a very safe product to use and is very effective. All Seasons Oil kills scale by smothering the insect. It is effective because it does not have to penetrate the “shield” of the scale. Scale can infest many different types of plants but Euonymus and Camellia seem to be the most popular choice of scale.
If you have a rose garden, you definitely know about thrips. Thrips are very small winged insects that feed very much like aphids and scale. They are most noticeably found in rose buds, aster flowers, and many other plants. They pierce the floral or foliar tissues and feed on plant sap. This can cause discoloration of flowers, or can cause flower buds to remain closed and eventually abort. Thrips are very small, and may be difficult to see. If you suspect thrips are damaging your flowers, gently open up flower buds and blow into the bud. If tiny bugs begin to move or fly, you have found your culprit. As with the previous insects, thrips can be controlled by using systemic products to prevent infestations. Sevin and All Seasons Oil can also be used to control established thrips populations. Fun Fact: Thrips is both singular and plural. You do not have a “thrip”, only thrips.
Leyland cypress owners beware: Bagworms want you! Bagworms can damage many other species of plants, but in our area, Leylands see to be the main course. Much like scale, bagworms are interesting pests. They are actually the larval form of a moth. They create a casing made out of silk and plant material (usually from the host plant) in which they carry out their life cycle. The adult female bagworms rarely, if ever, leave the case. The adult males breed with the females, who lay the eggs in the case and then die. When the bagworms hatch, they begin to build their own case. This is when the damage occurs. The young bagworms work themselves along plants and devour the foliage. The young worms then complete their case and continue through the life cycle. The casings can be somewhat camouflaged because they are generally made with the host plant material. Heavy infestations can occur in Leyland cypress and lead to plant decline and death. Eradication of bagworms from the landscape is a difficult chore. If plants are young and small, hand picking and removing the casings is the best way to control populations. If hand picking is not possible, Sevin can be somewhat helpful. As with the other insects, systemic products can help to prevent or control bagworms. This insect is another reason (aside from numerous disease issues) that Fairview recommends other plants in place Leyland cypress.
There are many other species of insects that can cause damage in the landscape. This is a list of the most common insects that our customers have questions about. Lace bug, mealybug, white fly, and spider mites (not an insect, it’s an arachnid) are all common pests in the landscape. It is important to remember that these insects are all a part of Mother Nature and will be present in most garden settings. It is also important to follow the directions on the bottle of any product that may be used. Proper ratios for mixing, frequency, and timing of spraying are imperative facts to know for the proper use of any insecticide or fungicide.