By: Bonnie L. Grant, Certified Urban Agriculturist
Animals are known for their fierce protection and devotionto their offspring, but did you ever wonder how insects protect their young?The instinct to preserve children of any species is strong and likely extendsto insects. Just as a mother lion keeps her cubs safe, it’s possible an insectparent will similarly watch over its young.
Do Insects Care for Their Young?
Do insects care for their young? Well, not in the same senseas humans or even other animals. Much of the insect life cycle consists oflaying eggs and moving on. Most species are not especially attentive parentsbut often do give their children a way of protecting themselves. Nature has away of creating the necessary defenses so young have a chance to grow up andreproduce themselves.
It is rare for both insect parents to care for their brood,but it does happen in a few cases. Wood roaches, dung beetles, passalidbeetles, and some barkbeetles engage in bi-parental care during some portions of the life cycle.
Burying beetle males are on the papa job full time in a rareco-parenting marathon. Hive and colony activity highlights group infant caresuch as in a beehive or ant colony. This involves many insects protecting theyoung. Bugs do exhibit behaviors like hiding eggs and providing food.
How Insects Protect Their Young
In addition to evolving insect defenses for offspring,active parenting comes in several forms. Some insects will gather nymphs oryoung onto their backs or around them to shelter them from predators. The giantwater bug father, for example, carries the eggs on his back until they hatch.The female Brazilian tortoise beetle gathers her young under and around her.
Other insects, such as wood roaches, do stick around for awhile as the young develop into adults. Wood roaches care for eggs for up tothree years until they hatch. Web spinner mothers stay with their young andprotect them in silken galleries. While unusual, insects protecting theirchildren does occur.
Still, it is the norm for insects to drop and run. What theydo leave behind are specialized defenses unique to each species.
Insect Defenses for Offspring
The more common way insect parents protect young is byleaving behind chemical defenses. Feces is a popular deterrent, for instance.It may form a shield, repel via smell or taste, and send a homing signal. Inthe case of dung beetles, both parents share in the young’s care, with the malegoing off to hunt while the female enlarges her brood balls. Mothers areusually concerned with their eggs and may leave behind a toxin or chemical thatwards off predators.
Spittlebugmothers leave froth around the eggs which hydrates them and shields them fromenemies. Eggs are deposited in secret hiding spots or coated with a protectiveshield.
Insects aren’t the most loving of parents, but they do tryto ensure their young’s survival with certain natural tricks.
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Preventing Apple Pests
Growing your own apple trees is relatively easy, but avoiding insect and disease damage to the fruit requires pruning and prevention.
Prune. Prune your apple tree every winter before you detect any signs of new growth. Eliminate crossing branches, watersprouts, and crowded growth. The following pointers will help keep pests at bay.
Eliminate hiding places. Pick up and destroy fallen fruit, which may contain grubs. Remove plastic and paper tree guards, where adult flies and moths may spend the winter. Replace them with wire mesh guards. Surround trees with mulch instead of grass.
Smother with oil. In spring just before new leaves emerge, spray trees with nontoxic horticultural oil. The oil smothers dormant insects and their eggs.
Know your pests. Three common insect pests that damage apple fruits are apple maggot flies, plum curculio, and codling moth. The best time to control these pests is while they are mating and looking for potential egg-laying sites. This is just before early to midsummer, when these insects lay their eggs on or near developing fruit.
Apple maggot flies appear in June or July to lay their eggs on developing apples. When the eggs hatch, the larvae burrow into the fruit. Trap flies with sticky red spheres and bright yellow 8- by 10-inch rectangles hung in the trees at eye level. Place spheres near fruit clusters about three weeks after flower petals fall use two traps for a small tree (8 feet tall or less), six traps for a large tree (10 to 25 feet).
Curculio is a 1/4-inch-long beetle that makes distinctive crescent-shaped scars on developing fruit. The grubs tunnel through the apples, causing the fruit to drop in early summer. To kill the adults, spray phosmet (Imidan) immediately after the blossom petals fall and again a week to 10 days later. (Wear protective clothing and avoid spraying during bee activity.) Nonchemical controls include spreading a tarp under the trees in the morning and shaking the tree to dislodge the pests. Also, raking up and destroying dropped fruit will reduce the local population of these pests over time.
Codling moths lay eggs on developing fruits shortly after petals fall in spring. Eggs hatch in a few days, and young larvae tunnel into fruits where they feed and mature, destroying the fruit in the process. The best remedy is spraying Bacillus thuringiensis kurstaki in the evening 15 days after petals begin to fall. Repeat five days later. The spray is toxic to caterpillars only.
Apple scab is a fungal disease that causes black splotches on leaves and fruit. It is most common and severe in the eastern U.S. where summer rainfall is common, but it occurs in all apple-growing regions. The first line of defense is to plant scab-resistant varieties such as 'Enterprise', 'Freedom', 'Gold Rush', 'Jonafree', 'Liberty', 'Macfree', 'McShay', 'Nova Easygro', 'Prima', 'Priscilla', 'Pristine', 'Redfree', 'Sir Prize', and 'William's Pride'.
If you've inherited a disease-prone variety, sulfur sprays can control the disease. Use liquid sulfur, spraying it over the tree once flower buds show pink. Repeat 10 days later.
To reduce the need for fungicides, choose only disease-resistant apple varieties when buying young fruit trees.
Avoid all-purpose fruit sprays because they kill many beneficial insects as well as the harmful ones.
Insects are the most successful living organisms on the Earth. That's just one reason it makes good sense to balance one against the other, rather than trying to kill pests with poisons. It is also true that in nature there are no good or bad bugs. All are trying to make a living in the way nature programmed them. But from a gardener's perspective, some insects help and some don't. It's smart to learn about and exploit insect behaviors. In this article you'll learn how to wisely purchase and use beneficial insects.
Using insects to control other insects has a long history. Ancient Chinese records describe the construction of bamboo runways to help predatory ants move through citrus groves, and for hundreds of years Yemeni nomads brought ant colonies from the mountains to control palm pests in oases. Modern biological control began in 1888 when a small lady beetle was brought from Australia to California. This effort, organized by state and federal agencies, saved the citrus industry from the cottony cushion scale and was successfully repeated dozens of times worldwide.
There are two kinds of beneficial insects: predators and parasites. Predators eat or otherwise destroy one or more other insect pests directly. Parasites complete their life cycles in a specific host, destroying it in the process. Today there are nearly 100 mail-order companies in the United States (and more in Canada and Mexico) either producing or selling several dozen species of predatory and parasitic insects. Most of these are used in agriculture, of course, especially in greenhouses. But a few are well-known garden beneficials.
Releasing large quantities of a beneficial insect into your garden can work in several ways. Sometimes it's like a biological insecticide: The bugs you buy go straight to your pests, clean them up and then disperse or die off. Sometimes the beneficials have limited effectiveness on target pests, but then go on to establish a local population of beneficial offspring that live on from year to year, helping to reduce the background level of pests. And sometimes the good bugs consume just a few of your pests before flying away.
When we say that one of the insects described below provides control, we mean that a release can make a significant dent in the population of the target pest. Most beneficials will eat many different kinds of insects, but eating a few isn't control. Praying mantises, for example, feed on a wide range of pests but almost never serve to control outbreaks of any of them. In many instances, the beneficials will only give you partial control, so you may occasionally need sprays, too. Be careful to select a time and a material that will do minimal damage to the bugs you have bought.
Often the best strategy is simply to increase the biodiversity of your garden. "Simplify" an environment--by spraying an insecticide or by growing only one kind of plant--and problems get out of hand quicker. Make an environment more complex and problems are less likely. Accomplish this in your garden by planting a wide range of plants and by not using broad-spectrum insecticides.
Learning to use beneficial insects will make you a smarter gardener. Start by ordering some catalogs. Most suppliers provide some direction on how to use what they sell, although the quality of these details--and the prices--can vary greatly. Shop for quality as well as quantity. When you realize it's time to resort to the bug busters, it's often best to phone your order in. Most suppliers are very aware of the need to transport living cargo quickly and use express shipping when appropriate.
The Home Gardener's Top Beneficials
There are about 50 "good bugs" raised and sold commercially today. Many are very specific to regional or agricultural pests. Some are expensive or only available in limited quantities. Others, such as the praying mantis, are common but of limited usefulness. Those listed here are widely useful and available.
This small wasp that parasitizes the greenhouse whitefly has a long history of success in greenhouses. It can work almost as well outdoors when greenhouse whitefly attacks tomatoes or other plants. But Encarsia is not particularly well adapted to control sweetpotato whitefly. It will naturalize only where greenhouse whitefly is found year-round, essentially places that are completely frost-free.
Order this parasite as soon as you notice a whitefly population building. Good control occurs, however, only when minimum average temperatures are at least 72°F (for example, 62°F at night and 82°F or more in the day). At those temperatures, the Encarsia wasp can develop as fast or faster than the whitefly population. Insecticidal soaps and horticultural oils that you might also use on whiteflies don't harm the wasps seriously. Two releases one to two weeks apart will last the whole season.
Lacewing larvae are voracious. They are sometimes called aphid lions, but will eat just about anything they can subdue, including thrips and small caterpillars. Lacewings are most commonly sold as eggs, mixed with a carrier like bran or rice hulls. You can also buy the larvae. They cost about 10 times as much as the eggs but may be a good value, given that ants and other predators often eat a great portion of lacewing eggs.
Purchased eggs or larvae are best used as a biological insecticide--sprinkle them near a serious outbreak of a pest. The larvae will feed in the area as long as there is plenty of prey, and then your lacewing population will disperse.
There is little point in buying adult lacewings. It's more economical to attract one of the dozens of species native to North America. No matter where you live, there should be wild lacewings nearby, though not in as dense a concentration as you get when you release 500 or more eggs from a supplier. The adults of most species feed on nectar and honeydew produced by aphids and other sucking insects like leafhoppers, whiteflies and mealybugs. You can build up the population of wild lacewings (and help keep the adults that hatch from the eggs and larvae you release) in your garden by applying a sugar and protein mixture that simulates this honeydew. Dribble it onto the foliage near your garden, and especially near a pest outbreak. Commercial preparations of these insect foods have names like Pred-Feed and Bug-Chow.
Lady Beetles (Ladybugs)
The most widely available biological control is the convergent lady beetle, Hippodamia convergens, which feeds on small soft-bodied insects, especially aphids. These lady beetles are field collected rather than reared in insectaries, largely because they aggregate in large masses in the foothills of California and are easily gathered when dormant. Typically, collected lady beetles have not matured eggs and are ready to migrate immediately, dozens of miles away. Releasing them in your garden is fun but does almost no good against a pest outbreak.
Recently one supplier has begun offering convergent lady beetles that it has "preconditioned" by feeding them long enough for eggs to mature. Another advantage to this practice is that parasitized lady beetles can be culled out, slowing the spread of the tiny wasp that kills them. Preconditioned lady beetles will stay in your garden as long as the food supply lasts, eating aphids and laying eggs to produce larvae that also eat aphids.
Coast to coast, convergent lady beetles are a very common native. There are more than a hundred other lady beetle species (some introduced) that feed on aphids, scale and other pests. You can concentrate local populations in your garden by attracting adults. Use the artificial honeydews, such as Pred-Feed, and plant nectar and aphid-host sources, especially alyssum, legumes or flowers in the family Umbelliferae (wild carrot, dill and the like).
This small wasp, Pediobius foveolatus, parasitizes Mexican bean beetle larvae. It's native to India, where it attacks a related insect. It cannot survive American winters in the bean beetle's range. Order the pedio wasp early in the season, when you first notice adult bean beetles. By the time it arrives for release, the bean beetle larvae will be starting to hatch. The wasps control bean beetles very succcessfully if introduced early in the season this way. They're more effective than the spined soldier bug, the only other biocontrol for bean beetles.
The Pedio wasp is not widely available and a little expensive. But it is very effective and fascinating to watch, and one release will protect gardens within half a mile.
Various species of mites are sold to control spider mites and thrips, especially on greenhouse crops and indoor plantings. Some of them also work on mite or thrips outbreaks on roses, strawberries, fruit trees, cucurbits, eggplant and other garden plants.
Each species has different requirements for temperature and humidity, so discuss your needs with the supplier at the time of ordering. All predatory mites require fairly high humidity (70 percent or more)--their effectiveness may be lower in dry regions. They also prefer to forage on plants without hairy leaves.
Release predatory mites early in the season. Watch carefully for incipient spider mite or thrips populations, then order predatory mites immediately by phone. The mites are perishable and require special shipping, one of the reasons for their high cost, around $20 per 1,000. Your concentrated population of mites will disperse when the food source becomes scarce, so you will need to order more mites if outbreaks occur later in the season. Predatory mites are very susceptible to soap sprays and other insecticides, so use soaps only before the mites arrive.
Nematodes, or roundworms, teem in the soil of lawns and gardens everywhere. Some are major plant pests but the great majority feed on soil microorganisms. A few prey on insects, injecting them with lethal bacteria, then feeding on the resultant "goo". Several strains and species of predatory nematodes are produced and sold. Many were originally discovered in soil of the southern United States, although they rarely become abundant even where they are native. Purchased nematodes generally need to be released annually to provide dependable control.
Steinernema carpocapsae is sold under the names BioSafe, BioVector, ScanMask and Exhibit. It is very effective against caterpillars and beetles that live in the soil. This is bad news for beneficial ground beetles but good news if you have problems with cutworms, cucumber beetles, corn rootworm, flea beetles and others. These nematodes also work on raspberry borers, squash borers (inject them into the stems) and peach tree borers (paint them on the trunks). Unfortunately, they don't seem to work as well on thrips, or root maggots and other fly larvae. New techniques of packaging these nematodes mean they can be stored several months at room temperature, which is why they are showing up in garden centers.
Heterorhabditis bacteriophaga works very well on all sorts of white grubs, which are serious lawn pests, as well as on root weevils. But it is more difficult to produce and more perishable, which is why it costs twice as much as Steinernema.
Although this beneficial occurs across North America, it isn't commonly found anywhere. Both nymphs and adults feed on caterpillars and the larvae of beetles, including Colorado potato and Mexican bean beetles. They can eat caterpillars that are so big that few other predators can handle them.
Because spined soldier bugs don't exist in high numbers anywhere, you can increase the population near your garden by buying and releasing them. There is only a single supplier of spined soldier bug. There is also a pheromone lure, the Rescue Soldier Bug Attractor, which is a unique product. Most pheromone lures draw only males, so are only good for monitoring insect populations. This one attracts females and is a good way to concentrate wild soldier bugs in your garden.
Trichogramma wasps parasitize and kill the eggs of all sorts of caterpillars. So tiny you need a microscope to see them, they occur widely in the United States, especially in the southern half of the country, but are rarely abundant enough to provide much control. They are economical to raise, however, and mass releases can be very effective against corn earworm, cabbageworms, loopers, hornworms, codling moth and other leaf-eating caterpillars. To get the right species of Trichogramma wasps for your climate and pests, discuss your needs with the supplier.
Because it's hard to spot pests' eggs and because Tricho wasps are usually cheap, the best strategy is to plan on weekly or biweekly releases to keep up with new egg laying. Many suppliers are glad to ship on this schedule all season, if you request it. The wasps arrive ready to emerge from eggs of their insectary hosts, which are glued to a card. Prices vary widely, so shop for a good deal.
Trichogramma wasps control the same insects that Bt does. Bt won't hurt the wasps or their developing young, so you can use Bt to kill caterpillars that escape the wasps.
Whitney Cranshaw is an associate professor and extension entomologist at Colorado State University.
Are Lacewings Organic?
Green lacewings offer natural aphid control for organic gardens in North America. Of course, they don’t just eat aphids – they are a great resource to control many other garden insects.
What makes lacewings an “organic” control? Since these beneficial bugs are regular inhabitants of most of North America, their presence in your garden doesn’t alter the ecosystem. That means that under federal standards, applying them to your plants will still allow you to qualify your harvest as organic.
Talk about a win-win situation! The lacewings eat all they want and you and your garden reap the benefit.
7 Eastern Screech Owls Befriend Blind Snakes
The eastern screech owl has hit upon a novel and creepy solution to the problem of ectoparasites. These owls always deliver food dead to their young—with one exception. That exception is Leptotyphlops humilis, a snake with vestigial eyes that resembles an large earthworm. While the owls sometimes eat the snakes, they more often simply drop them into their nest, and owls old and young leave the wiggly reptiles alone.
The snakes live in the nest, feeding upon insect larvae in nest debris. This greatly reduces the young’s chances of contracting parasites—nests with live blind snakes let nestlings grow faster and enjoy a lower mortality rate.
City birds may have hit upon a new variation to the blind snake strategy. They line their nests with cigarette butts, killing parasites like ticks and mites. They favor butts with a higher nicotine content, which kills more parasites.
Responsible Pesticide Use
Useful terminology found on pesticide labels:
This is the chemical component of a pesticide formulation that is toxic to the pest. Become familiar with the active ingredients. “Other” or “Inert Ingredients” are carriers, which may or may not be toxic to the target pest. Pesticide products generally are recognized by their advertised brand names. Pesticides with different trade names can have the same active ingredient.
The formulation of a chemical refers to the form in which a pesticide is prepared for sale. Some of the more common formulations that the gardener may encounter include “ready to use” (RTU), “emulsifiable concentrate” (EC), “flowable” (F), “granules” (G), “dust” (D), and “wettable powder” (WP). The same pesticide may be available in more than one formulation. Different formulations of the same pesticide may be more effective in certain circumstances and may be registered for different uses. It is important that the user read the label to be sure that the correct material is being selected for the job.
Days to Harvest
Some pesticides require a period of time for residues to dissipate before treated produce can be used safely. This information is found on the LABEL of the pesticide.
|Bacillus thuringiensis||Caterpillars (cabbageworms, cabbage loopers and others)||Microbial - apply when caterpillars are small.|
|Beauveria bassiana||Wide range of pests such as thrips, whiteflies, aphids, caterpillars, weevils, and Colorado potato beetle.||Microbial - more effective on immatures than large larvae or adults insects. Caution should be used when applying it when honeybees are actively foraging.|
|Insecticidal soap||Wide range of insects, especially soft-bodied aphids and whitefly and mites.||Synthetic - do not treat when plants are under stress. Soaps may burn plants. Toxic to invertebrates if spilled into water. Follow label precautions.|
|Iron phosphate||Slugs||Organic compound - component of a granular bait. Follow label precautions.|
|Neem (azadarachtin)||Aphids, cabbageworm and other caterpillars, earwigs, flea beetles, leafhoppers, mealy bugs, psyllids, spider mites, spittlebugs, squash bugs, stinkbugs, thrips, and whiteflies.||Botanical - toxic to bees exposed to treatment. Toxic to fish and aquatic organisms. Follow label precautions.|
Note: Pyrethroids are synthetic compounds whose structure and mode of action are similar to pyrethrins but they are not approved for use in organic production. There are many pyrethroids.
|Wide range of insects.||Botanical - highly toxic to bees, beneficial insects and fish. Slightly - moderately toxic to bird species. However, because pyrethrum residues break down quickly, the effect on beneficial organisms is reduced. Follow label precautions.|
|Spinosad||Caterpillars (such as imported cabbageworm, cabbage looper), leaf miners, thrips, Colorado potato beetle, borers, corn borer, squash vine borer, corn ear worm||Microbial - toxic to bees exposed to treatment. Follow label precautions.|
|Oils such as sesame oil. Can be petroleum, plant or fish based.||Wide range of insects and mites and their eggs.||Synthetic and natural - works by smothering. Oils may burn plants. Follow label precautions.|
Warning! Pesticides can be dangerous! Read and follow all directions and safety precautions on container labels. Handle carefully, and store in original containers with complete labels, out of reach of children, pets, and livestock.