Most areas of the county have received multiple rounds of showers and heavy rainfall over the past several days. That was the good news. The not-so-good news is that the rains provided attractive breeding sites for several species of mosquitoes and that mosquito populations typically start to significantly increase 7-10 days after a heavy rain, especially during our warm summer season.
Mosquitoes that serve as vectors of the Zika virus are on peoples’ mind nowadays. My colleague Dr. Sonja Swiger (Texas A&M AgriLife Extension entomologist at Stephenville, TX) noted that “While people enjoy outdoor activities and travel this summer, it’s important to remember that our first line of defense against Zika is to avoid being bitten by mosquitoes. The Aedes aegypti and A. albopictus mosquitoes that transmit Zika occur commonly in our backyards where their eggs are laid and larvae live in standing water. Like other mosquito species, they are active at sunrise and sunset, but commonly bite throughout the day as well.”
Concerns about mosquito-borne diseases this summer are prompting many of us to learn what to do to reduce the chances of mosquito bites in our own backyards and gardens. Fortunately, there are good ways to manage mosquitoes around your home at reasonable cost.
Homeowners should be aware that persistent pockets of stagnant water are more likely to become mosquito breeding grounds after heavy rains. Homeowners will likely be surprised at how many mosquitoes are homegrown in their own backyard and their neighbors’ backyards as mosquitoes typically do not travel far from their “birth place.” The Asian Tiger Mosquito, which is a dominant species in our area, has a very limited flight range of about 300 feet.
It would be well worth the effort to make regular inspections of your property for likely mosquito breeding sites and keep in mind the following guidelines:
– Overturn or empty objects that have collected rainwater including standing water in saucers under potted plants.
– Clear gutters and down spouts of debris so that rainwater drains properly.
– Remove water that collects on sagging tarpaulins or other covers on your house or property.
– Eliminate standing water in tires, buckets, trash cans, etc. Dr. Swiger also cautions homeowners to inspect trees for cavities which can retain water that can serve as breeding sites for mosquitoes. Tree cavities should be sealed with expanding foam.
– Empty and clean birdbaths weekly.
– Larger water-filled objects, such as water gardens that do not contain fish, can be treated with an insecticide containing the bacterium Bacillus thuringiensis israelensis (Bti), which does not harm fish, birds or mammals (including people). Mosquito Dunks is the most commonly available brand name of this insecticide. Mosquito Dunks look like small donuts complete with a hole in the middle. One Mosquito Dunk will effectively treat 100 square feet of surface water for 30 days or more.
Even though we look to the local mosquito control unit to provide widespread control of mosquito populations, area residents can have a significant impact on mosquito populations by checking for persistent pockets of stagnant water in their landscape.
Caterpillars on Citrus
Orange dog caterpillars are commonly found feeding on citrus trees. Caterpillars resemble bird-droppings—an ingenious disguise for protection from predators. If your citrus tree has only a few caterpillars, you can handpick them off.
Larger infestations can be treated with several applications of an insecticide containing Bacillus thuringiensis (such as Dipel or Thuricide). Applications should be spaced four or five days apart because this product does not last long in the environment and quickly breaks down. Bacillus thuringiensis is derived from a naturally occurring bacterium that only affects moth and butterfly caterpillars and does not affect people, pets, wildlife and many beneficial insects.
Be aware that the orange dog caterpillar is the larval stage of a beautiful swallowtail butterfly. Killing the caterpillars will stop emergence of adult butterflies. A few larvae on a single citrus tree will not kill the plant. So you have to decide if losing a few citrus leaves is a small enough price to pay for being able to enjoy some swallowtail butterflies.
Determining Ripeness of Citrus
Judging from comments from many home citrus growers, it appears that most citrus trees are carrying a heavy crop load this year. Many growers are interested in knowing when citrus fruit will be ready for harvest. Keep in mind that all citrus fruits only ripen on the tree. The best way to determine ripeness for oranges is to watch for the color to change to orange, then check for a slight softening of the fruit. Sometimes an opaque sheen will develop on the skin. Lemons are ready when yellow, and generally hold on the tree for months. Limes are smaller and ready when green; again, watch for a slight softening. Clip ripe fruit off with pruning shears instead of pulling it to avoid damage to twigs.
You usually can’t tell if citrus is ripe by looking at it. Most types of citrus will ripen between late November and early January. When some of the fruit reach full size, taste them to see if they’re ripe. Tasting them is the only way to know whether or not they are ready to eat. Try one and find out!
Homeowners should inspect trees for cavities which can retain water that can serve as breeding sites for mosquitoes. Tree holes near ground level are especially attractive to the Aedes mosquitoes that may spread Zika virus.
PHOTO CREDIT: William M. Johnson
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