Questions & Answers

This page contains questions (edited) we have received from our viewers along with our responses.  
We thought you might find this information helpful.     


   Some of my evergreen shrubs are turning white. It seems to be spreading. Looks like when we used to spray fake snow on our Christmas trees.  D. P., Howards Grove, WI; 6/7/11

   It sounds like spittlebugs have infested the evergreens. A forceful spray with the garden hose may be sufficient to control them.

   I have a weird clumpy, (maybe sticky) brownish orange growth that is all over my small evergreen ground cover.  Any idea?  Is it a fungus? Anything to get rid of it or do I need to pull the plants out?  It is on all of the evergreens.  A. C., Boulder, 5/14/11

   It sounds like the ground cover has juniper-hawthorn rust. Please see

   How can I remove mites from house plants without using pesticides?  Thank you.  K. D., Loveland, 2/8/11

   Mites thrive in dry, warm conditions.  Therefore, to control them without using pesticides, your best weapon is water.  Wash off the leaves regularly with water.  You can also spray plants with a weak solution of insecticidal soap periodically.  Mist plants to increase humidity.  You can also increase humidity by placing plants on a tray filled with a layer of decorative rocks or gravel and water.

   I have tiny gnat type bugs flying above my lawn in Boulder.  Not sure what kind, bluegrass I think.  What could these be?  K. A., Boulder, 7/16/10

   I can't be sure, but I suspect the flying bugs are the adult stage of sod webworms.  The adult stage is a tiny tan moth.  The lawn can be treated with an insecticide if it is showing signs of damage.  Otherwise, the moth is just a nuisance to contend with.

   What can I use to kill the little orange/red worms in the tips of the new growth on my Austrian Pines & Mugho Pines?  They cause the new growth tips to turn brown & die.  When I snap off the dead part, the worm is quite visible & alive.  Thanks greatly.  M. M., Johnstown, 7/4/10

A:    The little orange/red worms in the tips of the new growth on the pines are the larvae of pine tip moths.  The good news is that they won't seriously harm the plants.  The bad news is that there is little you can do about them right now.  Plants need to be sprayed with an insecticide when the new growth begins in May or early June.  For more information please see
Q:    We have a linden tree that is dropping an enormous amount of sticky sap for the past 2 years. The tree is about 20 years old. It is sticky and staining our deck black. Any help?  J., Toronto, Ontario, Canada; 7/6/09
A:    I suspect the linden tree may have aphids, which secrete a sticky substance called "honeydew."  Black sooty mold then begins to grow on the honeydew.  To control the aphids spray the tree with a strong jet of water and/or insecticidal soap.
Q:    Do aphids winter over in the garden; as in do they live in the soil or the compost pile over the winter? Are there preventive measures that I can take before they show up on my plants? I want to avoid the soap routine this season.
Thank you,  A. P., Lochbuie, 3/6/09
   Aphids do over winter, often as eggs, in gardens.  They may be on bark or other parts of plants.  Many over winter on one kind of plant and then move to another during the growing season.  Spraying with horticultural oil can smother the eggs.  Also, check frequently in early spring for aphids and start the soap routine right away to limit the population explosion!
Q:    Hi, I'm a novice gardener with a pest problem. My apple tree seems to have an infestation of rosy apply aphids, curling leaves and damaging incipient fruit. Also, my neighbor's ornamental shrub is covered with a similar white aphid that is now moving into my spinach patch. Both aphids secrete a sticky substance that covers the leaves and leads to a whitish dusty mold.  What should I do?  S. B., Boulder, 6/2/08
A:    Aphids can often be controlled by spraying plants with a strong jet of water.  Insecticidal soap is also helpful on trees and shrubs.  Aphids usually leave apple trees in late spring and spend summer on other plants.  Next year use horticultural (dormant) oil in late winter or early spring to kill over-wintering eggs on the apple tree.  Work with your neighbor to control aphids on the ornamental shrub so you don't have to treat them on the spinach.
Q:    Hi- I live in Durango, CO, and have several lilac bushes around my new property.  The leaves are being devoured around the edges so that they all exhibit a heavily serrated appearance.  I can sometimes see tiny black bugs on the leaves.  What are they?  Are they eating the leaves or is it something else?  What can I do about it?  Thanks a million-  L. K., Durango,8/2/06
    The black bugs on the lilacs probably are black vine weevils.  They commonly feed on lilacs causing the edges of the leaves to be notched, as you described.  The bugs feed at night.  The larvae feed on the roots and cause a lot of damage.  To control this pest you can spray the plants with Orthene.  Repeated applications may be necessary.
Q:    I live in Boulder and have a large tree in my backyard that sprays sap all spring and summer long.  The sap is sticky, clear with not much color, and lands on the patio furniture and our cars.  I do not know the type of tree, but it is at least 3 stories tall and the branches droop.  Little branches also grow out of the trunk.  What can we do to stop this?  J. F., Boulder; 5/10/06
    The sticky substance that drips from the tree probably isn't tree sap, but "honeydew" from aphids in the tree.  Spray the tree frequently with a strong jet of water to get rid of them.  You can also spray the tree with an insecticidal soap.  Stronger chemicals, if necessary, are available.  Because of the size of the tree you may want to consider hiring a tree care company.
Q:    We moved from Oregon 18 months ago. Back in the Pacific Northwest I would spray an oil based dormant spray in late January/early February. Spraying a dormant spray in the winter/early spring controlled the amount of chemical spraying you needed to do in the growing season when you were outside enjoying the garden.
   Last year was my first spring in Colorado. I seemed to miss the proper time to dormant spray. The instruction on the spray I had brought with me from Oregon stated that I should not spray when the nights went below 32 degrees. It seemed that the window of opportunity came and went within a week. One day there was frost on the lawn and the next day my deciduous trees were in bloom!
   I really want to spray some Aspen trees, ornamental vines, and roses with the dormant spray. We live in a new sub-division in the south Aurora area and I have spent a lot of time and money attempting to create a good foundation for a grand garden and yard in the future. I am working on the landscape step by step as I learn more and more about gardening in Colorado.  I look forward to the Home and Garden Show in two weeks.
   When is the proper time to dormant spray in Colorado? I went to a nursery and asked this question. They said there was no need to dormant spray. I don't agree.  I feel I can really be preventive now. I would rather not spray later in the year with my children and pets around.  Thank you. S. N., Aurora, 1/11/05
    There are dormant oils available that can be used when daytime temperatures are above a specified low.  You might want to purchase one of them.  That will allow you to spray on any nice day during winter or early spring.  Weather is unpredictable here.  If we get warm days the plants leaf out early.  I would try to spray in January, February or early March.  Any later and you may encounter plants that have begun to leaf out.
    Using dormant spray has advantages.  It smothers pests rather than poisoning them.  Aspens, roses and other plants that are highly prone to pests benefit from the use of dormant sprays.  It kills pests that over-winter on them.
    Enjoy the Colorado Garden and Home Show.  Seeing all the beautiful flowers in the middle of winter is a real boost to a gardener's spirits.

Q:    I have a Ficus Bush that seems to have brown spots on some of its leaves. I have just transplanted it to a bigger container & fertilized it . It's located in a well lighted area at my office . Why are these spots appearing ?  Any help is appreciated .  B. S., Bessemer, AL; 10/20/04
    There are several things that could cause brown spots on the ficus bush leaves. 
1) If the spots appeared after you fertilized the plant, it may have fertilizer burn.  Water the plant well to leach out some of the fertilizer.
2) Ficus bushes like bright light.  However, if the plant is next to a west or south facing window the leaves can scorch.  Bright, filtered light is best.
3) Improper watering can cause leaf problems.  Keep the soil slightly moist, not wet. 
4) Leaf spots may be due to disease.  Unfortunately, ficus bushes are prone to this problem.  A fungicide intended for use on houseplants may help.

Q:   I planted an autumn purple ash tree in early June. It now has new leaves which are being eaten around the edges. Some older leaves show holes within (not ragged around edges like the new leaves). Is there an insect causing this and should I spray the tree with insecticide?
   I also planted mugo pines in early June that are now showing brown needles toward the bottom which are shedding.  Is that normal?  K. M., Denver, 7/12/04
   The damage to the Autumn Purple Ash tree that you've described is typical of Brownheaded Ash Sawfly.  You can try to manage this pest by spraying the tree with a strong jet of water.  If problems increase you can use an insecticide.  Usually damage by this pest decreases in July, with May and June being the time of highest pest activity.
    It is normal for pines to shed some needles annually.  Also, the needle drop may be due to the plants' reaction to being transplanted.  Water them deeply and let the soil dry out before watering again.  Avoid over-watering.

Q:    Greetings,  I have a home in Winter Park on a wooded lot with lodgepoles and aspen.  There are approx. 15 aspen spaced out over the lot. The aspen have been afflicted with something that starts at the tip of the leaf turning the leaf black at the tip and working back into the leaf. Younger leaves are more susceptible.  The area between veins goes first turning light green to yellow then black.  It doesn't look like leaf spot or ink spot, but I am not sure. This is the third year of the infestation and it has spread tree to tree in those three years.  The leaves will wilt and drop prematurely weakening the tree for next year when only stunted leaves will appear.  On a single tree I did find small pustules on the bottom of the leaves which smacks of aphids but I saw no bugs on any tree.  Not sure how to proceed to protect the trees. Can you help?  M. L., Winter Park, 7/10/04
A:    From your description, I agree that the aspens do not have leaf spot or ink spot.  Do the young shoots blacken and curl to resemble a shepherd's crook?  If so, the trees may have Shoot Blight, also called Shepherd's Crook.  It is a common disease of Aspens growing in the mountains.  The spores of this fungus overwinter in fallen leaves and the dead shoots.  Clearing fallen leaves and pruning off dead shoots may help control this problem.  Prune when the tree is dormant and disinfect the pruners between cuts.  You may find this CSU Cooperative Extension fact sheet helpful:

Q:    We live in Colorado Springs and have an area of scrub oak near our house that has different size pods along the branches. It looks like some kind of hive or insect nest of some sort. What can we do to get rid of them?  S. B., Colorado Springs, 4/6/04
A:     I suspect the pods on the oak branches are galls created by rough bulletgall wasps.  Young wasps develop inside the galls.  Unfortunately, while the wasps are inside the galls, little can be done.  There are few effective controls for these wasps.  Insecticides can be used in fall when adults emerge. 

Q:    I need information on pine beetle kill in Colorado.  How prevalent is it?  Is there a map of Colorado showing attacked areas?  M. C., Greenwood Village, 1/22/04
A:    For information on pine beetles in Colorado I suggest that you contact the Colorado State Forest Service office in Fort Collins, CO.  Their phone number is 970-491-6303 and their e-mail address is  Another source for information is the USDA Forest Service, Rocky Mountain Region office in Golden, CO.  Their phone number is 303-275-5350.  Hopefully they can provide the information you need.

Q:    We have borers in our Aspen trees which are killing the trees.  We have tried lindane and other treatments to no avail.  What do you recommend we do?  Thank you for your anticipated reply.  E., Golden, 10/17/03
   Timing of treatment with an insecticide is really important when dealing with borers.  Borers within trees can't be successfully treated.  You must spray when the adults are active or laying eggs; that is, when they are on the outside of the tree.  Usually this will be in June, July and August for borers that attack aspens.  Lindane has been the main product used to control borers.  Products containing permethrin or carbaryl are also currently being used. 
   Borers attack stressed trees.  Healthy trees are less likely to be attacked.  The recent drought may have been a factor.  Keep the trees watered well, including watering them during winter if there is little snow.  If the trees had scale or aphid problems, spray them with a dormant oil product before they leaf out in spring.  Unfortunately, it is very difficult to eliminate borers.  Good luck.

Q:    This questions is in reference to house plants, but perhaps you can answer it for me:  I replanted some houseplants recently in a soil that I believe was not sterilized and developed a fungus gnat problem.  I tried using the Schultz-Instant insect spray which failed miserably.  What brand that I can easily find at the store would you recommend for this problem?  I prefer something I can either spray or mix with the water.  Thank you.  R. B., Aurora, 8/27/03 
A:    You might try Concern Multi-Purpose Insect Killer. Also, Fertilome has a Fungus Gnat product.  Schultz Insecticide Spray should be effective too.  Whatever product you use will require repeated applications.  Fungus gnats lay their eggs in the soil.  Larvae hatch from the eggs and develop there.  After a pupa stage they become adults and leave the soil.  When you spray, you are only killing the adults that are alive at that time.  New adults will appear within a few days that will need to be killed.  As long as eggs are hatching you will have the gnats.  Killing adults before they can lay eggs will eventually get rid of them. Yellow sticky traps placed near or in the pots can trap some of them.  Also, try to limit watering.  Moist soil promotes fungus gnats.  If possible, allow the soil to dry out between waterings.  A soil drench can be used to control larvae.  Knock-Out Gnats and Gnat Guard are two choices.

Q:    This is our first summer in this house we bought last year.  The house has a mature yard full of perennials.  About two weeks ago, I spotted numerous holes in some of the rose bushes and sunflowers.  One of the sunflower is not looking good at all.  I think the problem is earwigs.  Please let me know how I can organically get rid of them.   What can I do to help the damaged plants?  Thank you for your help.  A., Aurora, 7/9/03
A:    A number of insects, including earwigs, could be responsible for chewing holes in the plants.  Some steps you can take to manage pests include these:
       1) Hose off plants with a jet of water.
       2) Clean up debris such as fallen leaves and flowers that could harbor pests.
       3) Earwigs hide out during the day.  This provides an opportunity to collect or trap them.  You can place moistened newspapers in the flower beds in the morning and collect up the earwigs that hide there in late afternoon.
       4) Spraying the plants with insecticidal soap will control some pests.  Organic insecticides can be used if problems become severe.
       5) Keep the plants healthy by providing sufficient water, if possible with your water restrictions.  Stressed plants are more susceptible to problems with pests.

Q:    Comments on getting rid of gnats in flowers:  I have tried letting the flower dry completely before watering, I water from the bottom of the pot, I have those yellow things that attracts the bugs and I have used bug spray for gnats.  I still have them.  Do I have to get rid of my plants and start over or could I use a bug spray; i.e., one for killing flies, bees, etc. and spray my entire house?  I have been bothered since I brought 2 poinsettias at Xmas.  And, I am tired of these pesky things.  What can/should I do?  B., Muskegon, MI; 6/20/03
A:    Spraying your house will not solve the problem you are having with fungus gnats.  Continue to let the houseplants dry completely between waterings.  Also, continue to use sticky traps to capture adult fungus gnats.  Whitney Cranshaw, Colorado State University Cooperative Extension entomologist, suggests using bug sprays for houseplants containing pyrethrins or pyrethroid insecticides to control adults if other measures have failed to provide adequate control.  You also need to kill the larvae in the soil.  He suggests the use of a soil drench that contains neem or Bt (Bacillus thuringiensis) var. israelensis (H-14) strain.  These products are available at garden centers or by mail order. 

Q:    What is the best way to kill mites?  I have some killing the grass around my house.  M. B., Castle Rock, 4/23/03
A:    Mites that damage turf grass thrive in dry conditions.  Outbreaks tend to occur in lawns stressed by drought.  Recent snow and rain will help.  You should water your lawn to the full extent allowed by your local water restrictions.  If necessary, chemical control may be helpful.  Be sure to read and follow label directions.

Q:   We have a problem with our trumpet vine ( Campsis radicans).  It appears there are white scales that have grown on the stems but not on the leaves.  There appears to be no traces of mealy bugs or other insects.  However the plant is drying and losing leaves, first becoming yellow.  Could these be some sort of mealy bugs or scale insects?  G. P., 8/11/02
A:   The white scales on the stems are probably scale insects.  (Mealy bugs have a cottony appearance.)  Both are a common pest on trumpet vine.  Scale insects suck out plant juices causing leaves to turn yellow and look sickly.  Spraying with insecticides, unfortunately, won't help.  In fact, insecticides may do more harm by killing off natural predators.  Spraying the plant with a strong jet of water may help, or you can try scraping off the scales.  Hosing off the plant has the added benefit of removing dust that deters the natural enemies of scale.

Q:   I am having a problem with budworms in my petunias.  I noticed the problem about two weeks ago and I fear I am too late for Bt to work.  To make matters worse, I also have aphids on the petunias and they are in a container with other plants.  Should I try the Bt and an insecticidal soap, or should I call it a loss this year and pull the petunias out?  Will the budworms attack other plants?  J., Philadelphia, PA; 6/24/02
A:   Budworms commonly attack petunias, geraniums and nicotiana.  Occasionally other flowers such as roses may be attacked.  If plants are heavily infested it is probably best to get rid of the plants.  Handpicking the caterpillars at dusk when they are more active is helpful.  Also, Bt may still be an effective control even if it does not eliminate them at this point.  Budworms lay eggs that over-winter in the soil, so don't save and reuse the potting soil.

Q:   I have little black shiny bugs on my tomato plants and white alyssum. They are very tiny. What are they and how can I get rid of them?  Thanks for any help. I live in Arvada.  C., Arvada, 6/14/02
A:   The tiny black shiny bugs may be flea beetles.  Do they jump when disturbed?  Are there small holes or pits in the leaves?  Insecticides containing cabaryl or permethrin can control them if necessary.  Be sure to use only products that indicate they can be used safely on tomatoes.  Follow label instructions carefully.  Repeat applications may be necessary.

Q:   My aunt's house is becoming overrun with moths, inside and out.  She lives in Colorado Springs.  Can you give me an idea of what might be causing this problem and how she can eliminate them? It's getting impossible for her just to even sleep at night.  D. C., Westminster, 6/7/02
A:   The moths are probably Miller moths, a common nuisance in May and June in Colorado.  These moths begin life in eastern Colorado where the larvae feed on wheat, corn and other crops.  As the weather warms up they migrate to the mountains, passing through the Front Range.  While a nuisance, they do not chew holes in wool or cause damage in the home as other moths do.  
  Miller moths are attracted to light.  By reducing indoor and outdoor lighting you can reduce the number of these uninvited guests.  Be sure windows have screens that are in good condition to prevent entry.  Do not leave doors open if there is no screen door.  Once they get inside the house, use a fly swatter or vacuum cleaner to get rid of them.  Another little trick is to place a bowl or bucket of soapy water right beneath a lamp.  Moths will be attracted by the light and get trapped in the water.  The good news is they will soon be gone as they continue their trek to the mountains.

Q:    I have a few plants that I keep out in the summer and have to bring in during the winter. Some of them have white flies and I have tried spraying them with water and again with a pesticide. They still seem to come back. I do not want to bring them in the house with the flies still on them. Any advice? Thanks.  A. C., Broomfield, 11/3/01
A:    Whiteflies can be difficult to control.  First, hose off the plants with a strong jet of water.  This will get rid of some, but not all of the pests.  Next you will need to repeat several applications of an insecticide to kill off successive generations of whiteflies that are in various stages of development.  Be sure to treat the underside of leaves where the eggs, nymphs and a pupa-like stage of these insects are found.  Insecticidal soap, horticultural oil, pyrethrins, and neem extract are products to consider.  Be sure to read labels to see if the product is suitable for the types of plants you have.  Do not bring the plants into the house until they are insect free; otherwise, the whiteflies will spread to other houseplants.

Q:   Slugs are eating all my herbs!  What is an organic way of getting rid of them?  I have tried the little containers of beer, but that only seems to touch the tip of the iceberg.  S. K., Louisville, 6/15/01 
A:   Filling shallow containers with beer is a popular remedy for slugs, but it appears additional controls are necessary in your situation.  One of the best ways to control slugs without resorting to chemicals is the use of barriers. Wrap containers and raised beds with a strip of copper about 3 inches high. Also, you can spread a ring of diatomaceous earth or wood ashes around the outside of containers or raised beds.  Slugs are active at night and early in the morning.  Handpicking them off plants at those times is helpful.  Another option is to trap them by luring them into a daytime "hiding place."  Using rocks or other objects, place a board slightly above the ground near the plants.  (You can also use damp newspaper for this.)  Slugs will hide there during the day and you can collect them up and dispose of them.  If the slugs are hiding in mulch that you've placed around the herbs, you may want to scoop it all up and replace it.  You are wise to avoid chemicals.  Many baits are extremely toxic to wildlife and pets, resulting in their deaths.

Q:    We have a 40 year old Colorado Blue Spruce here in Boulder with what we have been told is a spider mite problem.  We were told by a tree service company to spray with dormant oil, but I have also heard that dormant oil will harm a Blue Spruce.  What can we use on it to get rid of the mites?  About what is a fair price if we need to have a service spray it with harsh chemicals?  Any suggestions on what to do?  J. T., Boulder, 10/26/00 
A:    Spider mites tend to be a problem in dry, hot weather like we had this summer. They often attack trees and plants that haven't received much water. Be forewarned, they over-winter as eggs or dormant adults on the bark of plants and trees they have infested.
   Water is the key to preventing or managing problems with spider mites. Spray the tree with a stiff jet of water to knock mites off the tree and kill them. Hose off the tree frequently, especially in times of low humidity and high temperature. Be sure to water the tree regularly throughout the year, including winter.
   Spraying with insecticidal soap may be helpful, but do not spray with insecticides. Mites are resistant to many of them and the insecticides kill off natural predators, such as lady bug larvae. Dormant oils smother mites and their eggs. However, some oils discolor evergreen foliage. Use only a product that states it can be used on spruce trees. 
   I am not familiar with the cost for spraying trees. I suggest you contact a couple of tree service companies to get a second opinion as to the tree's problem, the recommended remedy and the cost for treatment. Some companies will look at the tree and give an estimate for free.

Q:    I have a problem with little gnats in my indoor plants.  They hang around in the moist soil of my ivy and other indoor greenery.  They are a nuisance in my home.  Can you help me get rid of them?  C.D., Broomfield, 8/24/00
   The gnats in your houseplants are known as fungus gnats.  While they are harmless to people, they are annoying and can injure plants by feeding on roots.  They thrive in moist potting soils that are high in organic matter.  To control the gnat population in houseplants
    1) Avoid over-watering plants.
    2) Let the soil dry out between waterings.
    3) Use potting soil that drains well.
    4) Hang yellow sticky traps on or near plants.
    5) As a last resort, use an insecticide made specifically for houseplants that controls gnats.

Q:     I have planted gladiolas in my garden, and they are starting to bloom.  The blooms are not complete, however, and look as though they have some blight.  The ends of the blooms are withered, and they dry out before they open completely.  Can you tell me what this is?  M.F., 7/23/00
   Information that I have on gladiolus indicate they are susceptible to several problems, with thrips being the most damaging.  Leaves turn silvery, then brown and die.  Flowers are distorted, and have silver or brown blemishes. Badly infected plants may not produce flowers.
   To control thrips you can spray plants with a strong jet of water or spray with insecticidal soap.  However, this only gets rid of exposed thrips.  Many will be protected inside the leaves and flowers of the plants.  Therefore, you may want to use a systemic insecticide.  Granular forms that you work into the soil should perform better than sprays. 
   Thrips can over-winter inside the corm (bulb-like part of the plant).  If you conclude that your plants have thrips you may want to discard the corms rather than storing them during winter for re-use next year.
   For a more reliable diagnosis of what is causing problems with your gladiolus, I recommend that you take a sample of the damaged plants to your county CSU Cooperative Extension office or to a garden center that has trained staff available to diagnose problems.  

Q:     What do you know about getting rid of geranium budworms in large (3x3x3) containers?  Do I need to completely change the soil in these containers for this season if I want to continue planting nicotiana and petunias?  There are living roses, junipers, etc. in them.  From A. S., Denver, 4/11/00
   Geranium (tobacco) budworms are a real challenge to Colorado gardeners who want to include geraniums, petunias, and nicotianas in their flower beds or containers.  Controls are few since this pest is resistant to most insecticides.  1) Thuricide, Dipel and other insecticides that contain Bt (Bacillus thuringiensis) are somewhat effective on petunias, but provide limited control on geraniums.  Inspect susceptible plants frequently.  Timing is key.  You must apply Bt as soon as eggs hatch but before the caterpillars have entered the buds.  Once they are inside the buds they are protected from the spray.  2) Hand picking the caterpillars, especially at dusk when they are most active, provides some control when feasible.  3) The geranium budworm spends the winter as a pupa in the soil -- about 2 to 6 inches below the surface.  Cold weather (below 20 degrees F) will kill them.  When we have a mild winter you are wise to replace the soil in containers where they over-wintered--at least the top portion if the container is large.  4) Consider switching to ivy geraniums and other plants that are less attractive to geranium budworms. Good luck-- you'll need it with geranium budworms!

Q:    Do you have any tips on getting rid of aphids on roses?  From A. S., Denver, 4/11/00
A:     You can manage aphids on roses with several methods.  1) Aphids over-winter on rose canes as eggs.  You can rid your plants of many of these eggs simply by pruning prior to bud break.  2) You can spray the plants with a strong stream of water to wash away or kill them.  3) Lady beetles ("lady bugs") are a natural predator.  4) You can spray the plant with a diluted solution of insecticidal soap.  5) If the above methods aren't successful you can resort to more toxic chemical controls.  Rose systemics and contact sprays and dusts such as Orthene, Diazinon and Malathion are usually effective.  Be sure to read and follow directions on the product label carefully to minimize unwanted adverse effects.