Ladies and Gentlemen:
Spring is supposed to be here shortly, but the temperature outside is a little frosty. But this hasn’t deterred the insects. These are out and active:
1. Carpenter bees – Although good pollinators, these mimics of bumblebees can cause some structural problems in unpainted wood. They are often confused with bumble bees, but on closer look they can be separated, as their abdomen does not have a yellow band of hairs. These pests nest in wooden structures such as lawn furniture, handles on garden tools (shovels, rakes, hoes, etc.) and the exposed rafters of houses, barns, sheds, etc. These tunnels in the wood can run for several inches and weaken the structure of the infested wood. The tunnels, once completed, are used to raise the next generation. The female begins to collect a ball of pollen upon which she lays an egg and then seals off that segment of the tunnel. These cells are about one to one and a half inches long. The tunnels can be 8 to 10 inches long or more, so several cells can be accommodated. As the female goes about collecting pollen and laying eggs, the male acts as a guard and hovers around the hole protecting it from being robbed by other males for the pollen stored there. The males do not sting, but the female can and will sting if handled or caught in hair or clothing. To prevent damage to exposed wood, it can be sprayed with Timbor or Bor-A-Cur. These are organic materials made from borates. The wood to be treated is wet, and then the material is sprayed on, let dry, wet again and then resprayed. This treatment allows the crystals of the material to be absorbed into the wood, and when the bee tries to drill a tunnel the crystals cut the cuticle of the mandibles, causing the bee to bleed to death, since unlike us it cannot regenerate tissue once it’s damaged. Where infestations are found, sprays with pyrethroids and liquid soap can be used to chase them off or kill them. The initial tunnel usually will not cause much damage unless in a tool handle, but in wooden structures, once a tunnel is drilled, instead of using the same tunnel the next carpenter bee will extend the tunnel and use the new section for nesting. This is where the structural damage becomes serious. (Figure 1)
2. Azalea lace bugs – These little pests are beginning to emerge from the eggs laid in the leaf tissue last year. Those azaleas next to buildings that can receive the radiated heat from the buildings are the first ones to show injury. The adults and nymphs feed with piercing, sucking mouthparts, and this injury to the cells causes the upper surface of the foliage to appear stippled and gray in color. This damage makes the azaleas look bad, and the leaves will appear this way all season. There are three or four generations throughout the year, with the first emerging just after the plants begin to bloom and the last in the early fall. No spraying is recommended unless the adults or nymphs are found on the plants. Use a piece of white paper and knock the foliage of the azaleas against the paper. Where they are present, the lace bugs can be easily dislodged and observed on the paper. When they’re found, several materials can be used to manage this population. Orthene, malathion, Bayer Advanced Garden with Imidaclorpid or granular Merit, or cygon are all effective materials for management of this pest. Where sprays are applied be sure to check your pH and make sure it’s between 5.5 and 6.5 for optimum effect from your pesticide. This will reduce the amount you have to spray and be safer for the environment and cost less for you. (Figure 2)
3. Spider mites – Like the lace bugs, they will cause the leaves of plants to become stippled and turn gray. They can be found on many plants now but are particularly bad on citrus. They are small, eight-legged pests that are NOT insects. They feed through piercing, sucking mouth parts like many insects. The two-spotted mite is light green in color with 2 large black spots, one on each side of the abdomen. The European red mite is bright red with white hairs on the abdomen. Both can be controlled with miticides like kelthane or agri-mek, or with ultra fine oil or a combination of the chemical with oil. The oil can be used alone but will have to be repeated to manage the population properly. Usually 2 or 3 applications at 10-day intervals will provide the control desired. (Figure 3)
4. Leafminers – These small insects’ immatures tunnel and feed within the leaf tissue of citrus, vegetables and ornamentals. The tunnels damage the leaf’s ability to produce food for the plant and disfigure the leaves causing them to twist and roll. On citrus they attack the new growth, so with every flush of growth a spray may be required. On other crops, spray when the leafminers are observed in the foliage. The best control is an organic material called Spinosad. (Figure 4)
5. Honeybees – With the warming of the weather comes the growth and blooming of plants. Bees are attracted to flowers to gather nectar and pollen to support the hive and to produce honey. Two-thirds of all the food we eat requires pollination either directly or indirectly. Many of the berries that are food or ornamental are produced by the honeybee’s pollination. Although not the only pollinator, it is the most consistent and effective. Many people often confuse the bees’ activity around a plant gathering pollen as a swarm. A swarm is the division of an existing colony because of too-confined quarters. Sort of like when your son or daughter gets married and they move into their own home. Swarms are usually a mass of bees flying through an area or collecting on branches or other structures to start a new hive or to rest while the scout bees find a suitable nesting site. If you have a swarm or one is using you house to set up the colony, it can be removed by local beekeepers. Go to the LSU web site at www.lsuagcenter.com, click on environment and natural resources and then on bees and wasp. At this location there is a listing of beekeepers by regions of the state who can help with their removal. Normally when you have plants blooming the bees are usually gathering pollen and or nectar. (Figure 5)
6. Shot hole borers – This complex of little beetles covers several families or wood infesters. Infestations are brought on by some sort of stress on the trees and woody plants, like a cold snap after warm weather, drought, flooding or root or weed-eater injury. These little beetles are attracted to the pheromones released by the woody plants. The most common injury is in the tips of branches that have started to bud out and we get a frost or freeze that injures the buds and the terminals of the branches. The beetles attack and bore into these injured branches causing them to die. Sometimes the injury is to the trunks of trees and the attack point is there and you can find pencil-like stacks of sawdust coming from the entrance holes or the sawdust collected at the base of the trees. In many cases the tree branches can be pruned to remove the injury, but sometimes sprays are required. In cases where the trunk is damaged there is little to do to save the tree. That is because many of these little beetles do not feed on the wood as they bore into the trees but feed on a fungus they brought with them that infects the tree. It’s the fungus that causes the tree’s death along with the stress from the infestation. Where possible homeowners can use either Thiodan or a pyrethroid to manage these infestations. They should be used with an oil to get better attachment and penetration into the bark of the tree for control. (Figure 6)
| | Figure 1. Comparison of bumblebee and carpenter bee. |
| | Figure 2. Lace bug adults and nymphs and injury. |
| | Figure 3. European red mite and two-spotted spider mite. |
| | | Figure 4. Leafminers on citrus, boxwood, iris and dogwood. Leafminers can be flies, moths caterpillars or beetles. |
| | Figure 5. Honeybees are worth $400,000,000 in pollination services to Louisiana. Showing a wild colony in a tree and a swarm on a fire hydrant. |
| | Figure 6. Shot hole borers attracted to stressed trees, showing beetles and damage. |
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