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A Comprehensive Guide to Safe Biological Pest Control |
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NATURAL PEST CONTROL WITH LADYBUGS
Beneficial garden ladybugs for controlling pests in your garden are the most popular and widely used beneficial insects for commercial and home use. Ladybugs are capable of consuming up to 50 to 60 aphids per day but will also eat a variety of other insects and larvae including scales, mealy bugs, leaf hoppers, mites, and various types of soft-bodied insects. Ladybugs, also called lady beetles or ladybird beetles, are a very beneficial group of insects. Ladybugs are natural enemies of many insect pests and it has been demonstrated that a single ladybug may consume as many as 5,000 aphids in its lifetime. Ladybug adults have a very characteristic convex, hemispherical to oval body shape. The head is covered by a hood called the pronotum. Many species of Ladybugs are present in North America and they are common in most habitats across the commonwealth. They may be white, yellow, pink, orange, red or black, and usually have spots.
Ladybugs are among the most familiar beetles, easily recognized by their round, often spotted bodies, less than 1/16-3/8" long. Most are shiny red, orange, or yellow with black markings, or black with red or yellow markings. Both adults and larvae are predators, mostly of aphids. They are common on plants and often over-winter as adults in large swarms under fallen leaves or bark. In the West huge swarms of Ladybugs fly into mountain canyons, over-winter under leaves, and return to the valley in the spring. If food supply is good there are many generations a year.In fact, this is a type of warning coloration to other animals that may try to eat lady beetles. Like many of other brightly-colored insects, ladybugs are distasteful to predators. When disturbed, they may secrete an odorous, distasteful fluid out of their joints to discourage enemies. Did you ever see a little red and black beetle crawling along your window sill? It was probably a Lady beetle or just Ladybug as most people call them. Most species of Ladybugs are among our most beneficial insects as they consume huge numbers of plant feeding pest insects, mostly aphids. This fact and their attractive appearance have contributed to the generally good opinion of Ladybugs by most people. For instance, the French call the Ladybugs les betes du bon Dieu or creatures of God. Ladybugs belong to the beetle family Coccinellidae which means Little sphere. There are probably 4,000 species found world-wide and over 350 in North America.
Life Cycle and Habits
The length of the life cycle varies depending upon temperature, humidity, and food supply. Usually the life cycle from egg to adult requires about three to four weeks, or up to six weeks during cooler spring months. In the spring, overwintering adults find food, then lay from fifty to three hundred eggs in her lifetime (tiny, light -yellow eggs are deposited in clusters of 10 to 50 each) in aphid colonies. Eggs hatch in three to five days, and larvae feed on aphids or other insects for two to three weeks, then pupate. Adults emerge in seven to ten days. There may be five to six generations per year. In the autumn, adults hibernate, sometimes in large numbers, in plant refuse and crevices.
Amount of Food Consumed
Lady beetles, both adults and larvae, are known primarily as predators of aphids (plant lice), but they prey also on many other pests such as soft-scale insects, mealybugs, spider mites and eggs of the Colorado Potato Beetle and European Corn Borer. A few feed on plant and pollen mildews. One larva will eat about 400 medium-size aphids during its development to the pupal stage. An adult will eat about 300 medium-size aphids before it lays eggs. About three to ten aphids are eaten for each egg the beetle lays. More than 5,000 aphids may be eaten by a single adult in its lifetime. The lady beetle's huge appetite and reproductive capacity often allow it to rapidly clean out its prey.
They will feed on other pests, but are best known to eliminate the aphid population, and are one of the most active predators, searching from dawn to dusk for food. Ladybugs are shipped in the adult stage and when released should mate and lay eggs within 8-10 days.
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Eggs are football-shaped and orange in color and laid in circular clusters of 3-20 on the underside of leaves. Each female can lay 10-50 eggs daily. The larvae consume up to 400 aphids at a rate of 50-60 aphids a day in later stages. If food supplies are short they will cannibalize each other. Larvae live for three weeks before pupating.
After 2-5 days adults emerge and continue to feed. Adults will consume over 5,000 aphids each. Pollen and nectar are necessary for maturation of newly emerged lady bug adults, particularly before a winter hibernation season. Adults can survive on pollen and nectar for limited periods, but a supply of aphids or other prey is necessary for egg production.
Pests Attacked
Most lady beetles found on crops and in gardens are aphid predators. Some species prefer only certain aphid species while others will attack many aphid species on a variety of crops. Some prefer mite or scale species. If aphids are scarce, lady beetle adults and larvae may feed on the eggs of moths and beetles, and mites, thrips, and other small insects, as well as pollen and nectar. They may also be cannibalistic. Because of their ability to survive on other prey when aphids are in short supply, lady beetles are particularly valuable natural enemies.
Life Cycle
Within a year, there can be as many as 5-6 generations of ladybugs as the average time from egg to adult only takes about 3-4 weeks. In the spring, adults find food and then the females lay anywhere from 50-300 eggs. The tiny eggs are yellow & oval shaped and are usually found in clusters of 10-50, near aphid colonies. The eggs take 3-5 days to hatch and the larvae voraciously feed on aphids for 2-3 weeks before they pupate into adults.
In the fall, adults hibernate in plant refuse and crevices. They often do this in mass where several hundred adults will gather at the base of a tree, along a fence row or under a rock. They especially like areas where leaves protect them from cold winter temperatures. Like all beetles, the lady beetles have a complete metamorphosis with distinct egg, larval, pupal, and adult stages. Adults of one common species, the Convergent Lady Beetle (Hippodamia convergens), spend the winter in protected hiding places such as logs, buiIdings, ground covering vegetation, and the like, where many hundreds of individuals may cluster together. With the onset of spring the adults leave their winter homes and fly to fields and yards where mating takes place. The females deposit the eggs in clusters of up to a dozen per mass. The larvae hatch from the eggs in about a week and immediately start to consume aphids or other appropriate food. In a little less than a month they pupate and the pupal period lasts only about one week. When the adults emerge they too feed on aphids, but as fall approaches they may eat some pollen which supplies fat for winter hibernation.
Attracting Ladybugs in the Garden
Apart from aphids, ladybugs also require a source of pollen for food and are attracted to specific types of plants. The most popular ones have umbrella shaped flowers such as fennel, dill, cilantro, caraway, angelica, tansy, wild carrot & yarrow. Other plants that also attract ladybugs include cosmos (especially the white ones), coreopsis, and scented geraniums, dandelions.
Apart from planting attractive plants in the garden, you can also promote ladybug populations by elimination of spraying insecticides. Not only are ladybugs sensitive to most synthetic insecticides, but if the majority of their food source is gone, they won't lay their eggs in your garden. As difficult as it may be, allowing aphids to live on certain plants is necessary to ensure that there is enough food for ladybugs. In addition, resist the urge to squish bugs & eggs in the garden, unless you're certain that they are not beneficial.
LADYBUGS IN SPACE ON THE SHUTTLE
For years scientists have known that ladybugs will climb a stalk to capture aphids and aphids will escape by falling off the stalk with the help of gravity. The burning question that still remained was how would the aphid's defense mechanisms work in the absence of gravity?
In other words, what would the aphid do to escape the ladybug in space? Finally, in 1999 four ladybugs were sent into space on NASA's space shuttle led by Eileen Collins. Ladybugs and their favorite food, aphids, were sent to zero gravity to study how aphids would get away without the aid of gravity. After completing the mission, it was evident that ladybugs survived and did eat aphids in a microgravity environment. Seems like ladybugs could qualify being astronauts! Manifested aboard NASA’s STS-93 Mission, the “Ladybugs in Space” experiment probed the influence of microgravity on natural biological relationships— a concept important in considering future space travel and the possible colonization of distant worlds.
The experiment allowed students to observe the interaction of ladybugs and aphids on growing wheat plants in orbit and to replicate the experiment in their classroom as controls. Each day during the mission, students and teachers could use the Internet to access new images of the interaction of ladybugs and aphids in space. Students then, along with NASA scientists, analyzed those images utilizing the same counting and measurement techniques used in recording the results of the classroom control experiments.
As an integral part of the program curriculum, students studied the results from the experiment and were able to test hypotheses about the effects of microgravity on predator-prey relationships. According to Astronaut Pilot Jeffrey S. Ashby the science that is executed on the space shuttle these days is very complex and very difficult to understand for someone with my background of flying. One of the experiments that I do understand well, and is also very interesting, is an experiment that involves aphids and ladybugs. We are taking a small container with some leaves and aphids, and the ladybugs that are their prime predator. I'm told that the ladybugs on Earth will climb up a stalk to capture the aphids, and the aphids will use gravity to assist them to fall off of the leaf to escape from the ladybug.
The question is, how will these defense mechanisms work in the absence of gravity, and what will happen to the relationship between predator and prey? One of the things that extra time has allowed us to do is to come up with names for the four ladybugs that we have. I think they have been very appropriately named after The Beatles: John, Paul, Ringo, and George. We're taking these ladybugs up and we're going to release them and see what they do.
Ladybugs have been valued since medieval times as farmer's helpers. Some believed that the ladybug was divinely sent to rid crops of insect pests. In fact, that is how that ladybug got its name. People dedicated the bug to the Virgin Mary and called it. The Bug of Our Lady, which got shortened to the present name ladybug. In the Middle Ages, huge swarms of insects were eating up crops. The people prayed to Mary for help--and then ladybugs came and ate the pests. Another interpretation is that the ladybug rhyme is a cryptic reference to the fall of matriarchy and the rise of patriarchy, thus the reference to St. Ann who portends an eventual return to Goddess worship. Another interpretation is that this is a rhyme of resurrection and everlasting life, since the central figure is a beetle, one of the world's oldest symbols of the resurrection. More than 100 years ago, people in Europe thought that ladybugs could help them in many different ways. In Austria, people used to ask the ladybug for good weather. In Switzerland, people told their children that human babies were brought by ladybugs. People in northern Germany counted spots on the backs of ladybugs. Fewer than seven meant a big harvest. People in Central Europe believed that, if a girl caught a ladybug and it crawled across her hand, she would be married within a year.
RELEASE INSTRUCTIONS: When you are home, put the bag in a cool place (refrigerator) until late in the day or early morning. Do not release the ladybugs during the heat of the day or while the sun is shining. Sprinkle or irrigate the area before releasing, so the ladybugs will have a drink of water after their journey.
Being wild creatures, ladybugs will leave if they don't like their new home. You may have to experiment to provide the right environment for them. As I mention above, it is important to release the ladybugs in the evening or later because they will not fly at night and need a settling down period after being handled. When releasing the ladybugs, gently scatter or spread them out so each ladybug can find food immediately. To help ensure the success of your program, there are many ways you can improve the habitat for beneficial insects. One of these is to keep moisture levels high, as many beneficial insects require high humidity or ready-access to free water droplets. High humidity is more easily maintained by having plants close together. The garden or field should have various flowering plants to provide nectar and pollen for adult beneficial insects. In general, a mixture of closely-growing plants and flowers will greatly benefit both native and beneficial insects. This should result in higher productivity for your organic garden or farm.
Ladybugs Up Close
Adults have a very characteristic convex, hemispherical to oval body shape. The head is covered by a hood called the pronotum. They may be white, yellow, pink, orange, red or black, and usually have spots. In fact, this is a type of warning coloration to other animals that may try to eat lady beetles. Like many of other brightly-colored insects, ladybugs are bad-tasting to predators. When disturbed they may secrete an odorous sour fluid out of their joints to discourage enemies.
Adult females usually lay their clusters of eggs in the vicinity of aphid, scale, or mealybug colonies. The alligator-like larvae are also predators. They are spiny and black with bright spots. Although they look dangerous, lady beetle larvae are quite harmless to humans. After feeding on insect prey for several weeks, the larva pupates on leaves. Adults tend to move on once pests get scarce, while the larvae remain and search for more prey.
Folk Tales About Ladybugs
Many believe this began in England as a warning to ladybugs crawling on old hop vines. After the hops were harvested, the vines were burned to clear the fields. The adult ladybugs could fly away, the larva could crawl away, but the pupae could not leave the burning plants.
More interesting ladybug facts:
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