Category Archives: Lawn Pests

Grubs

By   October 8, 2015
grub

Grubs are dirty white and often curl up when exposed

Grubs are the #1 insect problem in most northern lawns. A grub is the immature larvae of a beetle. There are several types of beetles responsible, the most common are Japanese Beetles and Oriental Beetles. These insects spend a few weeks as adults, eating your broad leaf plants, then lay eggs in your lawn where they spend 10 months munching on grass roots.

If you have a heavy infestation, they may eat so much of your lawn’s roots that it can be rolled up like a carpet, although even lesser infestations can be harmful. Without roots, your grass cannot support itself and may die.

The simplest way of checking for grubs is to cut back a sample of turf with a shovel. Count the grubs in the top 3 inches of soil and replace and water the turf. Take several 6″ X 6″ samples from different locations. Most grubs are white or cream colored with dark patches, and have 3 pairs legs. Grubs grow up to an inch long. They’ll usually be curled up like a C when you find them in the ground. An occasional grub is ok, but if you average more than 2-3 per sample, your lawn probably needs treatment.

Grub control needs to be synchronized with their life cycle. They live for a total of about one year. Starting with eggs laid in late summer, they fatten up while eating your lawn until the ground freezes. Then they move deeper to stay below the frost line, and return to your lawn in the Spring with an enormous appetite. By mid-Summer, they mature in to beetles, eat your roses and other broad leaf plants, then lay thousands of eggs that start the cycle over again.

Fall is the critical time for killing grubs. If you wait until Spring, most of the damage will have already been done and the grubs will be much harder to kill. Most experts will advise that the best Spring Treatment is to fertilize and overseed, then wait to catch the next generation in the Fall when they are more vulnerable to insecticides. Of course, many professional lawn services will disagree and tell you a horror story about how the grubs will eat up all of your lawn and turn to eating your asphalt driveway if you don’t act right away…ignore hem and save your money for Fall treatment.

Controlling Grubs

By   October 8, 2015

Controlling grubs is a widespread problem and killing grubs is big business, so it’s not surprising that there have been many different ways invented. Some work better than others.

Let’s have a laugh first. There’s a company that created spikes that strap on to your shoes. As you walk across your lawn, the spikes are supposed to aerate the soil, controlling grubs at the same time. It sounds like a good idea, but when you’re working with a lawn any larger than a postage stamp, it would take Mrs. Smith’s entire tap dancing class weeks to get all of the grubs, and your lawn would be so torn up that there wouldn’t be much left.

If we eliminate the spike idea, that leaves 3 other management methods remaining. The first is a no-brainer. A good and healthy lawn can actually tolerate some grubs with no apparent effect. Maintain your lawn with a regular fertilization and liming program, mow it regularly and avoid cutting off more than 1/3 of the growth with each cutting, and keep it aerated. As you read through this website, you’ll notice that this is the same way to prevent weeds.

The next method is chemical. The most effective chemicals work only on newly hatched larvae, which are barely visible to the naked eye. So, waiting to apply insecticides until grubs have grown and are eating everything in site won’t be effective. If you know that you have grubs, it’s best to wait out the season until summer and attack when it will do some good.

Before we go on, let me express my personal opinion on insecticides. Most of them are poison, and most of the major chemical insecticides have been discovered to have some sort of effect on humans. Many that were once thought to be safe are now known to be hazardous and some are banned in the US. You might be familiar with the insecticides Dursban and Diazinon. Both were commonly used for lawn grubs but have now been restricted. If you need to use an insecticide, read the label carefully, follow the instructions, and use as little as possible.

This information is from the University of Rhode Island Landscape and Horticultural Program. They know a lot more about it than I do.

Dylox (trichlorfon) and Sevin (carbaryl). Dylox is a fast-acting material but is susceptible to alkaline hydrolysis. That means that it degrades in very hard or alkaline water or in a high pH soil very rapidly. One-half of the active ingredient will be degraded in 30 minutes at a pH of 9. Many public water supplies in Rhode Island are at pH 9 or higher. You also would not want to lime the lawn just before or after a Dylox treatment for the same reason. (If you are determined to attempt grub control in the spring – perhaps to reduce bird or mammal damage to the lawn, Dylox is one of the more effective materials available.)

Mach-2 (halofenozide) is an insect hormone mimic that is most effective against Japanese beetle grubs. It should be applied when beetles are flying (June 21-July 21). Low toxicity to non-target organisms. Soil half-life: 129 days. 

Imidacloprid (Trade Name: Merit) is an effective chemical treatment for grubs but, as noted above, it must be applied before eggs are laid. Treatments between April 1st and August 15th are generally effective.

The third major method of controlling grubs is biological.  Milky spore powder is a disease that kills Japanese beetle grubs but doesn’t seem to affect any other species. It’s not perfect, but it’s the easy way to go.  Once applied to the lawn, it spreads through infected beetles and remains active for years.  The drawbacks are that it takes a few years to build up the full effectiveness and if you spread insecticide and kill all of its host grubs, then the milky spore disease will die out too.

Moss

By   October 8, 2015

Moss is a common problem and is frequently blamed on low pH, but this is only part of the problem. Even though mosses are often found on soils with low pH values, they may also become established in areas of low fertility, shade, improper drainage, and/or packed soil. Often, two or more of these factors combine to create conditions unsuitable for vigorous turf growth.

A soil test will determine the pH and fertility level of the soil and recommend the necessary lime and fertilizer. The other factors can be determined by visual inspection.

Moss growing in a lawn

Moss growing in a lawn

Site conditions need to be addressed to eliminate the moss completely. Compacted soils can be loosened manually or mechanically, and poor drainage may sometimes be improved by minor regrading.

Trees can reduce the amount and quality of light your lawn area receives, and tree roots compete with the lawn for water and nutrients. Where the tree cover isn’t especially dense, removal of a few carefully selected lower branches may improve light conditions enough for moderate grass growth. Another option is mulching or growing plants more suitable to the site or planting a shade tolerant type of grass. There are many types of ground cover that will thrive where grass has a tough time.

Once the pH and other conditions are resolved, the moss needs to be physically removed before reseeding. It should come up easily with a rake as the moss does not have deep roots or anchors. Grass won’t grow unless the seed can make physical contact with the soil. There are some commercial moss killers on the market that contain ferrous sulfate or ferrous ammonium sulfate, but they’re not always useful and they can stain concrete walks or patios. Sometimes it’s easier to just skip the killer and rake it off.  Conditions still need to be improved or moss will return, and the moss killers leave behind dead moss which still needs to be removed.

On the flipside, moss transplants easily and can make a great groundcover in rock gardens or out of the way places.  It doesn’t stand up well to traffic and isn’t good for walkways.

Biological Control

By   October 8, 2015

Given enough time, nature usually finds a balance through biological control. There’s a famous quote from Jonathan Swift:
Big bugs have little bugs
Upon their backs to bite them.
Little bugs have littler bugs.
And so, ad infinitum.
Modern plant science has found a way to put this saying to work with several instances of “littler” bugs that attack the bigger bugs that harm grass. Biological control is a growth area in plant science now, and many of these biologicals are still new or in the testing stage.

Some bacteria cause disease in insects, call it biological warfare among bugs. The most common bacterium used against turf insects in Bacillus thuringiensis, often called Bt. Bt works by producing a toxin which paralyzes the insects gut, so the insect stops feeding right away and later dies. New Englanders are familiar with Bt for its effectiveness against Gypsy Months. It’s also effective against other types of caterpillars, but it doesn’t affect anything else. A new strain is currently being tested against white grubs and appears to be effective.

Another species of bacterium causes a disease in Japanese beetle grubs. Bacillus popilliae, sometimes called Milky Spore, causes “milky disease” in the grubs. Infected grubs take on a very milky appearance and are very flaccid. It’s action is very slow though and sometimes takes years to build up effectiveness. Milky Spore disease is available now and, although somewhat expensive, offers good value because of it’s long lasting effectiveness.

Neither of these bacteria are 100%, but can reduce the population enough so that it’s target bugs are no longer a problem.
Similar to bacteria, some fungi can cause disease in or in insects. It’s almost like a terminal case of athlete’s foot. Several of these fungi already exist naturally, others have been identified and need to be adapted for use here. One of the “native” fungi is Beauveria bassiana, which attacks chinchbugs and billbugs. Especially in cool, wet springs these insects may be found covered with tiny strands of materials that looks like cotton candy. These strands are mycelia of the fungus, which has invaded the insect body and attacked the internal tissue.

Another fungus, Metarhizium anisopliae, appears to be quite effective against white grubs in the soil. Researchers are commercializing this now and have hopes for its success.

Insect Growth Regulators, known as IGRs, are naturally occurring hormones that confuse the insect’s development. and prevent it from reaching adulthood. Several IGRs have been developed for such insects as whiteflies and mosquitoes, and at least one is being tested for white grubs. With my collection of pets at home, I’m a frequent user of Precor, an IGR that prevents fleas from maturing. The idea is that only adult fleas bite and reproduce, and preventing them from reaching adulthood ends the cycle.

 Nematodes

Nematodes are small parasitic worms that can carry bacteria inside their body, so when the nematode penetrates an insect victim, it releases bacteria, which break down the internal tissues of the target insect, resulting in death by infection. As the insect dies, the nematodes reproduce within the cadaver, and the juvenile nematodes pick up some of the bacteria and move on to new insects.
These are called Entomopathogenic Nematodes (“entomo” = insect; “pathogenic” = causes disease) and are already effective against several turf insects. The big prize will be when they finish development of nematodes that attack white grubs. Researchers are getting close.

Endophytes will be covered more in the grass seed section. Some species of grasses contain endophytes, which are fungi which produce substances which are toxic to certain insects. Endophytes occur in some perennial ryegrasses and fescues and have been incorporated into some commercial cultivars. They are effective in the suppression of chinchbugs and billbug populations and are active against cutworms and webworms as well.

Insects

By   October 7, 2015

There’s no way around it…your lawn has insects…lots of them…and that’s the way that it should be.

This page will cover only the types of insects that can be harmful to you or your lawn, and how to control them. The key word is control. Your lawn is outdoors and part of nature. There’s no way that you are going to get rid of all of your bugs and our attempts to eradicate the little critters may also remove all the beneficial insects that do more good than the insects we’re trying to remove.

Before we go on, let me express my personal opinion on insecticides. Most of them are poison, and most of the major chemical insecticides have been discovered to have some sort of effect on humans. Many that were once thought to be safe are now known to be hazardous and some are banned in the US. If you need to use an insecticide, read the label carefully, follow the instructions, and use as little as possible.

Here are the most common insects that are found in, on, or under your lawn:

Ants Ants don’t eat your lawn, but their tunnels and hills might be a problem.  Southern lawns might also have Fire Ants, a particularly agressive type that cause painful bites.

anthill

Anthill

Earthworms Earthworms are generally beneficial and don’t harm your lawn. Unfortunately, moles find them very tasty and dig underground tunnels looking for them.

earthworm

Earthworm

Fleas Fleas don’t harm your lawn, but they may fall of of a passing animal and lay eggs which grow up to look for their own animal hosts.

a flea

A flea

Grubs

Grubs are the larvae of several species of beetles. They are whitish or grayish, have brownish heads and brownish or blackish hind parts, and usually lie in a curled position. They hatch from eggs laid in the ground by the female beetles. Most of them spend about 10 months of the year in the ground; some remain in the soil 2 or 3 years. In mild weather they live 1 to 3 inches below the surface of the lawn; in winter they go deeper into the soil.

They burrow around the roots of the grass and feed on them about an inch below the surface of the soil. Moles, skunks, and birds feed on the grubs, and may tear up the sod in searching for them. You can estimate the grub population

grub

Grub

Japanese Beetles The Japanese Beetle is about 1/2 inch long and has a shiny metallic-green body; coppery- brown wings and six small patches of white hairs along each side and the back of the body, just under the edges of the wings. They usually appear after the 4th of July and are active for 4 to 6 weeks.

Japanese Beatles dine mostly on broadleaf plants, where they gather the energy needed to lay eggs that become grubs that feed on your lawn.

japanese beetle

Japanese beetle

Earwigs Earwigs don’t harm your lawn or people but their looks and crawling habit are intimidating to some.

earwig

Earwig

Ticks Ticks aren’t harmful to your lawn, but may fall of of a passing animal and live there until they can find another animal to bite.

tick

Tick

 

Moles

By   October 7, 2015

Moles are a real pain! Just when you have your lawn looking good, ridges start to appear. So you end up doing a funny dance, the “mole-in-my-lawn two-step”. It’s a cross between the jump and the mash.

Molehills caused by digging moles

Digging by moles causes molehills

Actually, your resident moles are looking for food. They dig through the soil, eating insects as they go. Earthworms and grubs are haute cuisines to them, but just about any insect will do.

Aside from creating a mess, moles actually do very little harm. They are insectivores and eat only insects. The only harm that they do to your lawn is the ridges that they leave behind, and in some cases their tunneling exposes some of the turf roots to air. On the plus side, a mole can eat 100+ grubs and other bugs in a single day…not a bad appetite for an animal the size of a chipmunk.

A single mole can dig 15 feet of tunnel overnight, then sometimes they seem to go away for a few days. Don’t celebrate too early because there’s a good chance that they’re still there, but just digging too deep for you to see. Or, worse than that, the female has gone to her den to care for a litter of babies.

There’s no shortage of advice on how to get rid of them. Everyone seems to have a sure-fire method that works, but the truth is, eliminating moles is very hard. The most popular method is large-scale treatment with insecticide. This seems to be the most common, perhaps because there’s money to be made in applying the treatments. Since Because moles feed on a variety of other invertebrates, not just grubs, applying insecticides to kill grubs in a lawn in hopes of depriving moles of their food supply is not generally effective. It may just increase the tunnels as moles look further for other sources of food.

Trapping is the most effective and practical method of controlling moles. There are several styles on the market, and most of them work if you follow the directions. Be persistent with the traps, if you eliminate one or two moles from a good feeding area, others will soon move in. There’s no way to be rid of them forever.

A search of the web turns up some unusual suggestions for ridding your yard of moles. Too bad that most of them don’t work:

  • Fumigants or gas-bombs may look good to see smoke coming up from the burrows, and may make the user feel good, but a mole usually has numerous burrows and escape tunnels.

  • Baits rarely work as moles don’t eat grain based materials. A lot of other birds and animals do, which then get eaten by dogs and cats who later die.

  • Broken glass, razor blades, chewing gum, and even human hair have been tried, but the results aren’t consistent. In all probability, the moles have just moved deeper or to another part of the yard. They’ll be back.

  • There are a few plants that seem to work. Marigolds and Castor beans have been studied, but you spread them out across the lawn and still have a real lawn. Several companies have tried a spray on Castor extracts, but the ground has to be continually saturated with them, and the results aren’t proven.

  • Windmills, whirly gigs, and electronic repellents can annoy you more than they annoy the moles.

Actually, there’s one other effective measure of control. Some dogs like digging after them. Borrow a beagle or dachshund. Of course, you won’t have much lawn left when they’re through, and you’ll have to stay by them for a while because, although they like the hunt, they rarely kill the mole because moles taste bad.

Critter Damage

By   October 7, 2015

Lawns suffer two types of common critter damage… chemical burns when a passing animal decides to use your lawn for a potty and digging damage when animals look for or bury food.

Animal poop problems are the result of too much of a good thing…urine and feces contain a heavy concentration of nitrogen.  Grass needs some nitrogen to live, in fact, fertilizer it is the primary component of fertilizer.  However, the concentrations in animal waste are much higher than your lawn can take, so you end up with a dead spot surrounded by a dark green ring that grows quickly as the concentration tapers off.

There’s not much that you can do to prevent critter damage unless you catch it early. A thorough watering can sometimes dilute the nitrogen before it does its damage, but once the grass is dead, the only solution is raking and reseeding.

Squirrels are common causes of critter damage

Squirrels are common causes of critter damage

Squirrels look at your lawn as a super-sized food storage area.  The ground is nice and soft and easy to dig, so they bury their acorns in the Fall and dig them up again later.  There’s not much that can be done to prevent squirrels…if you have oak trees, they’re going to collect and bury the acorns.  A dog that never sleeps might keep them away, but then you’ll also have to find a dog that never poops if you want to keep your lawn pristine.

Grubs Attract Critter Damage

Skunks and Raccoons are a different story than squirrels.  They dig for food, mostly grubs.  The long-term solution for this type of critter damage is to get rid of the grubs.  Your varmints might still dig for earthworms, but this is less likely.  Unfortunately, grub control is only effective during certain times of the year.  At the same time, your grubs aren’t smart enough to run away from a skunk, so a pet skunk won’t get rid of the grubs…other than the ones they eat!

Trapping these animals is futile as, once you trap the troublemakers, others soon move into the “good eating” territory. In addition, safely trapping skunk isn’t easy.

Crabgrass

By   October 7, 2015

Crabgrass is an annual grass that often becomes a problem in lawns.  Some areas of the country call it by different names.  Officially, it’s from the Digitaria genus but may be called finger grass, fonio, and a bunch of other names that I can’t print.  Whatever it’s called, it’s is junk.  It has a thick, course structure which looks out of place in normal turf.  It’s also very aggressive, crabgrass seeds germinate in the late spring and early summer and out-compete the domesticated lawn grasses.

picture of crabgrass also known as finger grass

Crabgrass aka Finger Grass

The plants are annual and die out with the first frost, but while they are living, each plant can produce up to 150,000 seeds. The plants leave voids in the lawn when they die, providing a place for the next year’s seeds to germinate.

Fortunately, crabgrass is easy to control. It needs warm bare soil to germinate, so most healthy lawns will block most of its growth.  There are several pre-emergent herbicides that prevent the crabgrass seed from germinating.  Timing is critical, though, apply it too early, and spring rains can wash it away before it does it work.  Apply it too late and, well, you missed the bus for preventing it from coming up.  Once crabgrass has sprouted, it’s difficult to kill without harming the rest of your lawn. In most of the northern US, an easy way to tell when to apply a crabgrass pre-emergent is when the forsythias are in full bloom.

Like another big lawn nuisance dandelions, some species of crabgrasses actually serve a useful purpose.  The seeds of some varieties of folio are considered millet and are popular in Africa and the Orient where they are ground into flour and used for baking or fermented for beer.

One of the pre-emergents is an organic corn gluten meal.  The others are chemical and, like all chemical herbicides should be applied with caution. Crabgrass prefers lawns that are under fertilized and mowed too low, so a healthy lawn is the first line of defense.

Pre-emergents need to be applied before the seed germinates.  Throughout the Northeast, the guideline is to apply pre-emergents at about the same time as the Forsythia bloom.  Don’t apply it too early as Spring rains may wash it away, or too late as pre-emergent means before (pre) the seeds germinate.  Once they start to grow, it’s tough to kill.

Unfortunately, most pre-emergents also prevent regular grass seed from germinating.  So if you are overseeding within a few months, use the special pre-emergents that won’t affect regular seed.

Lawn Disease

By   October 7, 2015

Lawn disease is usually caused by a fungus which grows from spores that are always present in lawn soil. The fungus is usually harmless, but when extreme weather conditions or faulty lawn care causes stress on the grass, the fungus can spread.

The fungal disease shows up as dead or dying lawn and usually strikes after extreme stress. Check for it after intense weather like drought, excessive rain or high humidity. Diagnoses are sometimes difficult, here’s a quick test. Pull up the infected lawn area. If the dead turf pulls away easily from the roots, it’s most likely that insects have eaten the roots. If the dead sod does not pull up easily it is probably a fungal lawn disease.

Proper care can usually prevent lawn disease, but sometimes our finicky weather can work against us. Water carefully, one or two heavy waterings a week rather than daily light ones. Aerate you lawn every 3 or 4 years, and overseed it with a new type of grass seed every 4 years or so to introduce new resistant varieties. Most important, be sure to mow your grass no shorter than 2 inches and don’t cut off more than a third at a time. Leave the lawn clippings on the grass.

Some common lawn fungal diseases include:

  • Brown patch – Round brown areas. The grass will first look water logged and then brown and dry. To combat this lawn disease use slow release nitrogen fertilizer in the spring. Improve drainage and remove all infected grass clipping.
  • Dollar spot – Light brown or tan spots the size of silver dollars. To get rid of this lawn disease feed your sod in the spring and fall. Apply light nitrogen frequently and be sure to remove and destroy infected grass clippings.
  • Fusarium blight – red-brown rings with healthy grass in the center. This lawn disease is usually caused by drought. Water you lawn frequently and reseed with disease-resistant seeds.
  • Powdery mildew – makes the grass blades look white or gray. The blades may turn yellow and wilt. This lawn disease likes to attack new grass. Correction of powdery mildew is to remove causes of excess shade, aerate your lawn and be sure not to over water or over fertilize.
  • Pythium blight (Cottony blight) – makes the grass looks greasy in areas with the affected outer areas black with white or gray mildew. The treatment is aeration. Don’t over fertilize or over water the diseased area, and reduce nitrogen applications.
  • Rust – The grass blades develop rust bubbles. Mow your lawn weekly and destroy all infected clippings. Be sure to feed, water and fertilize regularly.
  • Red thread – looks like areas of pink grass. You can actually see red or rust colored threads on the grass. This lawn disease loves cool humid climates. Fertilize in spring and fall. Add lime as needed, improve drainage and remove all infected grass clippings.
  • Snow Mold – white or pink spots on your lawn in spring. To prevent this lawn disease cut your grass short in fall and do not remove the clippings. Do not fertilize your lawn after mid-summer and improve your drainage.
  • Stripe smut – blades appear to be striped. The treatment is aeration. Be sure not to over water the area and remove all infected thatch.
  • Slime molds – patches of white, gray, or yellow slime. When the slime dries it looks gray, yellow or black. Aerate regularly and remove any thatch. Cut your grass to the lowest recommended height possible.

Insecticides

By   October 7, 2015

Healthy lawns should require few, if any, insecticide treatments. Insecticides are only a last resort.

If you find that you need to use an insecticide, read the label carefully, take appropriate precautions, use as little as possible, and follow directions carefully. Keep in mind that almost all insecticides are hazardous to humans in one way or another, some are toxic to pets and wildlife, and most kill some of the beneficial insects along with the targeted ones.

Over the years, almost every major insecticide that was once thought to be safe has had either cautions or warnings posted. Many have been banned and for good reason. I’m a do-it-yourselfer, but this is one area that I call in the experts….and I’m not talking about the lawn care companies that send in a bunch of teenagers with a tank truck to drench your lawn.

Commonly used synthetic insecticides include:

  • Dursban: Used for chinch bugs, cutworms, flea beetles, sod webworms, white grubs, armyworms, caterpillars, ticks, fire ants, fleas, wasps, mosquitoes, and ants.
  • Diazinon: Used for billbugs, chinch bugs, cutworms, flea beetles, sod webworms, and white grubs & Japanese beetles.
  • Orthene: Commonly used on cutworms.
  • Sevin: Used for billbugs, white grubs & Japanese beetles, caterpillars, ants, fleas, mosquitoes, and ticks.

In addition, there are some botanical insecticides. These are derived from plants and natural sources, and can still be hazardous:

  • Pyrethrin: Pyrethrin is derived from pyrethrin flowers and is a medium to highly toxic insecticide that will kill many different types (broad-spectrum) of insects at once. It is commonly used to spot-treat areas of a lawn. Try to avoid run-off into areas that contain fish, as it is toxic to them also. Commonly used on white grubs, armyworms, beetles, webworms, green bugs, and caterpillars.
  • Neem: Neem oil is an extract from a neem tree. Neem is relatively low-toxic for animals and is used both for treatment and prevention, mostly for white grubs and caterpillars.
  • Sabadilla: Sabadilla is derived from sabadilla plant seeds. It’s a relatively low-toxic botanical insecticide used on chinch bugs, webworms, armyworms, green bugs, and grasshoppers.

Biological insecticides are much safer, but also a bit more expensive. Biologicals include Endophytes, a fungus that grows in certain varieties of grass, and Bacillus Thuringiensis, commonly referred to as “BT”, is a bacterium that, when ingested, will destroy insects by eating at the inner lining of their guts. It is useful for sod webworms, armyworms, cutworms, and moth larvae. Another form commonly referred to as Milky Spore (Bacillus Popilliae) is used to control white grubs (Japanese Beetles).

Insecticidal soaps are a biodegradable treatment derived from salts of fatty acids. They are usually applied with water and soak the soil to kill the target insects. These soaps work by penetrating the cell-bodies of insects and are usually only effective on soft-bodied insects. Insecticidal soaps are commonly used for white grubs, chinch bugs, sod webworms, and billbugs.

Predatory insects are “good” bugs that eat “bad bugs”. Since most bugs are generally not a nuisance, it is important to understand that nature often has a way to balance itself out. Insects such as ants, ground beetles, ladybugs, wasps, big-eyed bugs, and even animals like birds can be helpful in controlling your “bad” bug populations by either feeding on, or parasitically attacking them. Many pesticides kill these predators if you’re not careful. If you have to use insecticides that can harm or kill these “good” bugs, try to limit the use (if you can) to spot-treatments on limited areas.