With the arrival of warm weather, also comes the arrival of summer’s threats: insects.
While some people may hate insects simply because they are so buggy, for gardeners, each year can feel like a new insect battle to determine which pest is destroying their plants and how to defend their crops from complete destruction.
Here are some of Michigan’s most pesky pests along with how to get rid of them, said David Lowenstein, an integrated pest management expert and consumer horticulture educator at Michigan State University.
Sawflies
Sawfly larvae, which are particularly a problem for roses, feed on leaves that have a chewing mouthpart that causes “glazing,” an effect that occurs when the insects eat the material between the leaf veins, leaving the remaining veins and plant tissues to collapse into holes. .
Sawfly larvae look like caterpillars, but Lowenstein says it’s important to note that there is a difference between the two in order to control pests. Insecticides that normally kill caterpillars are ineffective on sawflies because sawfly biology tolerates the chemicals.
Lowenstein says pesticides like insecticidal soap or Neem oil can be used to kill sawfly larvae, or they can be easily removed directly from plants and thrown into a bucket of soapy water.
Boxelder Bugs
Boxelder bugs, also called box bugs or maple bugs, are more of a visible pest than a nuisance, Lowenstein says. Elderberry bugs feed only on elderberry seeds and leaves, so they do not cause damage to most plants.
“They appear in large numbers, which causes people to be concerned when they see 50 to 60 insects on a tree or plant,” Lowenstein said. “Most of the time they are aggregator insects that don’t cause damage in the garden and I wouldn’t do anything about them.”
Boxelder bugs may be more of a concern when temperatures drop in the fall, as they can invade outdoors or enter homes. But again, they shouldn’t cause structural damage and can easily be vacuumed up with a shop vacuum or sprayed onto the side of a house.
More:Rubin: Good news. It’s not too late to bring butterflies and hummingbirds into your life
Slugs
After passing through hatching season, slugs may be more visible around this time throughout Michigan, especially in cool or shady, moist areas, munching on ornamental plants and sometimes vegetables.
Lowenstein says there are several ways to control the number of slugs in your garden:
- Reduce crowding in areas of your garden that might be overgrown or crowded, which will give slugs fewer places to hide.
- Aerate your soil in poorly drained areas, otherwise moist soil will also be a good place for slugs.
- Sprinkle diatomaceous earth around your plants or other problem areas to destroy the slugs’ exoskeletons and kill them when they come in contact.
- Set beer traps by filling a small container or pan with cheap beer. The yeast in the beer attracts the slugs, then they crawl into the trap and drown. However, Lowenstein recommends checking the traps regularly and replacing them as necessary in case the container fills with dead slugs or the amount of beer decreases.
Lily beetle
Unlike some of the other listed pests, lily leaf beetles are more of a problem in southeast and central Michigan, particularly because they are an invasive species that does not have many natural predators.
Additionally, in the larval stage, the bright red lily-eating beetle covers itself in droppings to appear inedible to predators.
Lily beetles can be handpicked from plants or garden owners can try treating an infestation with insecticides, but Lowenstein says if you already have lily beetles, they are likely to come back.
“Unfortunately, these insects don’t seem to be going away in southeast Michigan,” he said. “It’s been a pretty tough year for lily leaf beetles, so if you have them one year, there’s a good chance you’ll have them. I’ll have them next year too, so you might want to treat your lilies in May, that’s when they will start to come out.”
However, Lowenstein shared that he and a Michigan State University entomology professor were working on a project, inspired by a successful experiment on the East Coast, to control lily leaf beetle numbers through manipulation of a parasitic wasp. The wasp lays its eggs inside the larvae of lily beetles, killing the larvae. Lowenstein said they hope to release wasps next year in areas where lily leaf beetle damage is high.
Four-line pushpin
Four-lined plant bugs are what Lowenstein calls generalists: They eat ornamentals, weeds, grasses and just about any other plant in your garden. However, they will not actually kill the plant.
The insects have a piercing, sucking mouthpart that leaves brown circles when they feed on leaves, and although the damage is only cosmetic, the insects move quickly, so it may appear that the plant has contracted a leaf disease. day to day.
Lowenstein said it’s best to leave the insects alone and let the plants grow, but if gardeners really can’t stand the stains, they can use an insecticidal soap to treat the plant. However, he emphasizes that it is best to treat plants that have not yet been exposed to the four-lined plant bug to prevent them from suffering irreversible damage; for plants already filled with brown circles, it is unfortunately too late.
Because the insects feed on weeds, Lowenstein says it might also be helpful to go out and pull weeds to eradicate their food source.
More:Scientists try to solve the mystery of bird flu: why there are so many viruses in Michigan sewage
Japanese beetles
The Japanese beetle is another generalist species, feeding on vegetables and leaving behind holes that resemble skeletonized leaves on ornamental plants.
Although the beetles only emerge in the summer, they spend the spring living in the soil as larvae and feeding on lawn plants, which can cause browning no matter how much water sprayed by your watering system.
“We get a lot of questions about ‘Why isn’t my lawn doing well?’ “And a lot of times that’s due to grub damage,” Lowenstein said. “Another way people realize they have grubs is if their lawn is completely dug up by wild animals that like eat larvae. There will be a lot of holes, and if you pull out your lawn and see more than 10 to 15 grubs per square foot, that’s an indication that you may want to consider treating grubs in the lawn, and the best time to do it is from August to October with an insecticide.
Once the Japanese beetles are adults, Lowenstein says you can handpick them from your plants and install netting or another similar barrier to keep the beetles out.
According to him, insecticides should then only be used in extreme cases and pheromone traps should not be used, no matter how attractive they may be. Traps do a very good job of attracting Japanese beetles, but as soon as too many of them flock in and fill the trap, you end up with more beetles in your lawn than you started with. Pheromone traps are best for commercial use or for multi-acre properties, Lowenstein warns.
Tomato horns
As adults, tomato hornworms transform into five-spotted moths, but in caterpillar form, the insects can wreak havoc on your tomato plants.
Hornworms can completely defoliate a plant and can bore holes into fruit and other produce.
Fortunately, tomato hornworms can be easily plucked from a plant and thrown into soapy water to kill them. Or, you can remove the insects from your plants and set them aside to sell; Hornworms can make a good staple food for pet reptiles and amphibians, which are normally sold in pet stores for more than a dollar per worm.