Insects – Echter's Garden Talk

Understanding Japanese Beetles in Your Garden

If you’re a gardener in Colorado, chances are you’ve encountered the voracious appetite of Japanese beetles wreaking havoc on your plants. These metallic green and copper-colored pests are more than just a nuisance. They can quickly decimate a garden if left unchecked. Let’s dive into what makes these beetles such a challenge for gardeners and how you can manage them effectively.

Identifying Japanese Beetles
Japanese beetles (Popillia japonica) are easily recognizable by their distinctive coloring: metallic green bodies with copper-brown wing covers. They are about half an inch long and have small white tufts of hair along their sides, which can sometimes resemble spots.

You’ll often find them congregating in groups on plants, particularly those with large leaves like roses, linden trees, and grapes.

Damage Caused by Japanese Beetles
These beetles are not picky eaters — they’re indiscriminate feeders. Their known diet includes over 300 plants. They chew through leaves, flowers, and even fruits, leaving behind skeletonized foliage that can quickly turn your once-vibrant garden into a ragged mess. Their feeding habits can weaken plants and make them more susceptible to other stressors, potentially leading to plant death in severe infestations.

Life Cycle of Japanese Beetles
Understanding the life cycle of Japanese beetles is crucial for effective management. They have a one-year life cycle that begins with eggs laid in the soil during mid-summer. These eggs hatch into grubs that feed on grass roots, causing damage to lawns and other grassy areas. By late spring of the following year, the grubs pupate and emerge as adult beetles, typically around June in Colorado.

Grub Stage Damage: Grubs feed on grassroots, which can lead to brown patches in lawns and weakened turf that easily pulls up like a loose carpet.
Adult Stage Damage: Adult beetles emerge and feed on foliage, flowers, and fruits, causing visible damage within days.

Protecting Your Landscape
Managing Japanese beetles requires a multi-pronged approach that addresses the damage they cause at each stage of their life cycle.

In the grub stage

Beetles will be burrowed into your lawn. There are a number of products available that target grubs in lawns and have proven to be effective against Japanese Beetles.

Products like Milky Spore (a bacterial disease of grubs), beneficial nematodes (parasitic organisms that target grubs), and grub control products such as GrubGONE! or GrubEX! can help reduce grub populations in the soil without harming beneficial insects.

Milky Spore (Paenibacillus popillae) is an organic product that is easy to use and will protect your landscape for the next ten years. It is a spore that affects Japanese Beetle grubs and nothing else! Yes, you read that right. It will not harm anything else in your garden. That means it can safely be used in the lawn, in the vegetable garden, and throughout your landscape. (Note: Expect this product to develop over time. It takes 3-4 years to build up enough of the spore disease to be noticeably effective)

Beneficial Nematodes (Heterorhabditis bacteriophora) seek out and kill all stages of harmful soil-dwelling insects — including Japanese Beetles. They are tiny worms found in soil that target young stages of pest insects, like larvae, grubs, nymphs, and pupae. They are a natural and effective alternative to chemical pesticides, and have no detrimental effect on non-target species such as ladybugs, earthworms and other helpful garden insects. Releasing the nematodes into your garden is a simple process. They are sold in an easy-release powder that dissolves quickly with water. For application, you can opt for a standard watering can or use a hose-end sprayer or pump sprayer to apply.

GrubGONE! is a natural and effective product with the main ingredient being Btg (Bacillus thuringiensis galleriae). Commonly found in nature, these bacteria can live and multiply within the bodies of insects, and produce spores and protein crystal toxins which can result in death of the insect host. It is a granular which should be applied in the spring, and then again in mid- to late summer when adult beetles will re-enter the turf to lay eggs and overwinter.

GrubEX! is a granular pesticide (Chlorantraniliprole 0.08%) that should be applied in spring or early summer. A single application can prevent grubs of all kinds from damaging your lawn all season long, especially killing the Japanese Beetle larvae (grubs) so they never get the chance to develop into adults.

In the adult beetle stage

Japanese beetles will be actively flying and feeding on plant material in your landscape. A number of strategies can be employed to mitigate damage and get rid of the adult beetles.

Handpicking adult beetles can sometimes be effectively employed in small plantings. The beetles are easily picked or dislodged; shaking infested plants over a collecting container in early morning when temperatures are cool can be particularly productive. It is best to physically remove them from your plants with a gloved hand, but don’t squish them! Squished bugs emit pheromones, which end up attracting more beetles. Take the captured beetles and toss them in a bucket of soapy water.

BeetleGONE! is the first Bacillus thuringiensis galleriae (Btg) bio-insecticide to control adult beetles (plus the larvae or turf grubs) at a level of efficacy equivalent to chemical standards, but without the side effects or off-target damage to beneficial insects and pollinators. Unlike other biological or chemical grub-control products, BeetleGONE! can be used as a curative treatment for grub control as well as a preventative treatment. It works by making the foliage inedible to the beetles. This is a powder that you mix with water to apply. (Should be reapplied every 7-10 days)

Beetle traps, which use pheromones to attract beetles into a bag or container, can be controversial. While they can capture large numbers of beetles, they might also attract more beetles to your yard. If you choose to use traps, place them at least 30 feet away from your garden to draw beetles away from rather than into your plants.

Dealing with Japanese beetles requires vigilance and a strategic approach. By understanding their life cycle, identifying their damage, and employing a combination of cultural, biological, and if necessary, chemical controls, you can protect your garden from these invasive pests. Experiment with different methods to find what works best for your specific garden environment and remember to always follow product instructions carefully.

By taking proactive steps, being persistent, and staying informed, you can keep your garden thriving and beautiful, even in the face of challenges posed by Japanese beetles.

For a more detailed look at Japanese Beetles and possible controls, check out this informative fact sheet from the Colorado State University Extension:
Japanese Beetle Fact Sheet by Dr. Whitney Cranshaw

What’s Bugging Your Plants?

It’s that time of year when the pesky pests come out to munch on our favorite garden plants. The warmer the weather, the faster those tiny eggs hatch. Before we know it, an army of aphids (or other pests) have decided to call our plants “home”. There are some things to know when determining how to manage pests in the yard. First, you’ll need to identify what you have in order to choose the best course of action. Some pests can be managed with a strong spray of water from hose, others may require an insecticide. Most insecticides target select pests. If you don’t know what you have, clip a small section of plant that is affected and put it in a sealed, clear plastic bag. Take the sample to your local garden center or county extension office for identification.

The most common pests are aphids, spider mites, white fly, Japanese beetles, earwigs, scale, and slugs. There are a plethora of other insects, like tomato horn worm, psyllids, flea beetles and geranium bud worm, too. Many will be managed by Mother Nature’s predatory insects. Others, however, may require a bit of direct attention.

Aphids are probably the most common garden pest. They are usually green, but may be black or red, or even woolly. Aphids are pretty easy to identify. You’ll be able to see adults with their distinctive horn-like spikes over their back legs.

Aphids are pretty easy to manage. If it is a light infestation, like the one pictured above, a hard stream of water will knock them off, pretty easily. Ladybugs love to munch on aphids. Release them in the cool evening hours and they’ll be making mince meat out of those aphids in no time. Your ladybugs will stay in the area as long as they have a food supply. Once your aphids are under control, they are likely to move on to another food source. They can also be controlled using Neem oil or pyrethrin sprays. Both are safe and effective, natural products. Avoid applying any chemicals on hot sunny days. Apply them in the morning or evening, to avoid damage to foliage.

Spider Mites

These tiny little creatures usually go without notice until we see their telltale webs. For the most part, they hand out on the back of leaves, sucking the life out of our plants. They are a little smaller than a pin head, making them difficult to see with the naked eye. If you hold a piece of paper under an infested leaf and tap the leaf, some will fall onto the paper, making them easier to see. Spider mites aren’t fond of moisture. Direct water spray from a hose nozzle will usually knock them off. That said, they are persistent little buggers. Spraying them with a pyrethrin spray, or Neem oil would be prudent. As with any chemical that is not a systemic, you’ll want to spray ever 5-7 days for 2-3 weeks, in order to catch each life cycle.

Fall and Winter Control of Pests and Disease in the Landscape

The fall and winter season provides an opportunity to control pests and disease in the garden. Fire Blight is a bacterial disease that affects certain species in the rose family, especially apples, crabapples and pears. Applying Bonide Copper Fungicide while the trees are dormant is one method of control. Copper sprays are toxic to many species of bacteria and should be applied prior to bud break while trees are still in dormancy because they may damage leaves and young fruit.
Control the overwintering stages of many insects on trees and shrubs with All Season’s Spray Oil. Be sure that the air temperature is above 35 degrees F and do not apply if plant tissues are wet or rain is likely. The oil will smother overwintering aphids, spider mites, eriophyde mites, scale and their eggs and larvae.

If you had problems with powdery mildew or other fungal leaf spotting on lilacs, aspen and maples, be sure to clean up any leaf debris and dispose of it. Clean up of affected leaves is one of the most effective controls of powdery mildew. It is best to avoid overhead watering of the affected plants during the growing season if possible.
Most pests and disease problems result from stress to plants. In Colorado our greatest stress factor for plants is drought. Remember to continue watering plants in your landscape through the winter when temperatures are above normal and precipitation is below normal. Water mid-day when temperatures are in the 40 to 50 degree F range. During prolonged dry periods, water at 3 to 4 week intervals.

What’s Bugging Your Garden?

Once the heat of summer comes along it seems every aphid, spider mite, and leaf miner and thrips pay a visit to my garden. In the case of most garden pests, high summer temperatures create the perfect environment for rapid reproduction. Learning to identify the what creatures are munching on the garden plants is the key to gaining control. Once identified, we can learn a little about their life cycle so we can choose the best method of control.

Many garden pests can be controlled with a garden hose and a strong spray nozzle. If we scout out the garden regularly, chances are we can find them before they become a serious infestation. Most pesticides (organic, natural, or otherwise) are effective on specific pests. There isn’t a single pesticide that is effective on every garden pest, which is all the more reason we really need to identify what’s chewing away on our plants in order to form a responsible plan of attack. After all, no one wants to spray anything willy-nilly through their garden. Not only would that be a waste of time, energy and money, it may also pose a risk to those beneficial insects we actually need in our gardens.

Thrips are super tiny insects that aren’t easily seen without magnifying lens. Most often we see Western Flower Thrips in the garden. They are slender, tan insects, about .2 mm long. They are so tiny, we usually see the damage to our plants long before we notice the insects. They are notoriously difficult to treat because they often feed on the tender tissue inside buds or the folds of immature foliage. They are sucking insects so they often leave buds and leaves deformed and scarred. Thrips are particularly attracted to blue flowers. Knowing this, I usually plant a few dark blue petunias and use them as sentinel plants. Once I start to see stippling on the flowers and areas that have clearly lost their color due to tissue damage, I can bet they have decided to make a home in my flowers. A strong spray of water can drown them. If they persist, try using an insecticidal soap, neem oil or pyrethrin spray. Thrips are also known to spread tomato spotted wilt virus, spreading it from plant to plant as they feed.

Below you can see the damage and the thrips.

Aphids are probably the most common and devastating garden pest. They may be green, red or black. They are plump, soft bodied, little insects and we can usually identify them by their cornicles (tubes that sort of look like horns protruding from their abdomen). Aphids are also sap sucking insects that leave our plants with deformed, stunted buds, blooms and leaves, reducing productivity of vegetables. Aphids are also capable of spreading many plant viruses. They are, however, one of the easiest insects to control when they are found early. Hosing off plants with a strong stream of water will go a long way toward eliminating aphids. Neem oil and pyrethrins are very effective treatments, too. Aphids can build up a tolerance to pesticides with each generation, so alternate whatever you use to insure the best results.

Aphids pictured below.

We often see spider mites after we’ve noticed their webs. These teeny-tiny insects can make foliage appear gray-green and speckled. We see the damage primarily on the back side of the leaves. The top of the leaves may appear a bit discolored, faded and the speckling may be obvious. They can be hosed off with a strong stream of water. They may also be treated with insecticidal soap, neem oil, or pyrethroids.

Spider Mite on Croton leaf, pictured below.

Spider mite damage to Mandevilla pictured below.

It’s important to note that any chemical, organic or otherwise, should be used according to the directions on the label. All chemicals are expected follow specific protocols established by the EPA. In other words, the label is the law and there is no substitute for reading the fine print. Don’t spray on a windy day when the chemical may drift onto other people, plants, wildlife, or toward beneficial insects. Water the day before you spray and spray in the early morning or late evening hours. This helps reduce the risk of damage to your plants from the spray. Be sure to wear gloves and the appropriate protective gear when handling any chemical.