nsects are an essential part of the ecology, but that doesn't mean you need to let them destroy your hard work in your garden or share your harvest with them. Knowing which Arizona garden pests are most likely to invade your garden is an excellent first step in preventing an infestation and protecting not just your garden, but your neighbor's as well. Read on to learn more about Arizona garden pests that might be preying on your garden, and a few tips on safely dealing with them.
Pale green aphids are small pear-shaped insects with soft bodies that prefer warm weather. Temperatures pushing into the mid-80s are when you are most likely to notice these little green pests clustering in large numbers around stems and the base of leaves. They survive on the plant juices and secrete a sticky green substance.
Most plants are perfectly adapted to handle a few aphids. However, aphids tend to overstay their welcome. Female aphids give birth to hungry live young called nymphs, which rapidly develop into hungry adults in just a few short weeks, and the cycle continues.
An extended and growing family of aphids can quickly develop into an infestation. Infested plants will start to exhibit distorted growth and yellow leaves that may drop off.
Try not to use too much nitrogen when fertilizing your garden because this can stimulate the plant to grow too fast and produce the tender new growth that aphids prefer.
Spray with neem oil when you notice aphid clusters or apply a strong water jet from the hose to dislodge them and reduce their numbers. Aphids are a ladybug's favorite food, so try to attract them to your garden with appetizers like coriander, dill, catnip, mint, and nasturtium. Plants that produce pollen and nectar will also attract ladybugs to your garden.
Cabbage worms may be tiny at the start, but you should not underestimate the destructive power they can have in your garden as they ravenously feast to sustain their rapid growth. The cabbage moth lays its eggs on the underside of leaves, and once they hatch, the larvae will go to town on your plants with an insatiable appetite. In just a few weeks, the fully-grown larvae will create a cocoon on one of the leaves to start the cycle again.
You will usually spot the holes in the leaves before you notice the perpetrators of the destruction. They are voracious eaters and will quickly decimate a plant in just a few days. If you aren't checking your plants regularly, you may already be too late by the time you notice the damage.
The best way to spot cabbage worms is to check your plants daily for holes, even tiny ones, as that is a sure sign of new larvae. Cabbage worms are a lovely shade of green, so they blend in well with the foliage. Look upon any holes with enough suspicion, though, and you will spot them happily munching away.
There are many ways to deal with cabbage worm if you want to do it organically, including:
Agaves are decorative plants Arizonians love to feature in their xeriscape gardens. Xeriscape is a fancy term for landscaping with a focus on reducing or eliminating water.
Unfortunately, the agave snout weevil loves the agave as much gardeners do. Agave snout weevils are about a half-inch long beetle with a distinctive downward-facing nose, perfect for piercing into the agave plant's core where it will lay its eggs.
Once the grubs hatch, they will devour the agave's heart before burrowing into the soil to pupate. The weevil previously limited itself to desert regions and Mexico, but populations have started popping up throughout the US and other countries.
Check your agaves for damaged tissue around the area where the leaves meet the stem. Lower leaves will be wilted and slope towards the ground. If the infestation has been going for a while, it will be easy to push the plant on its side. The core will have a foul smell, and you will likely notice a squirming mess of cream-colored, brown-headed grubs.
Dealing with an agave weevil infestation is a challenge, but the beetles are mostly attracted to the century plant. If you know your area has been affected by the snout weevil, using smaller agave varieties may help stave off an infestation.
You don't have many organic options for treating agave weevil, other than to use less desirable agave species and remove the affected and surrounding plants. There is an organic solution under development that uses pheromones to attract and trap an adult beetle searching for a mate, but this is still in the testing phase. A broad-spectrum insecticide like imidacloprid or cyhalothrin granules applied every spring will help protect your plants.
There are more than 150 species of blister beetles feeding on Arizona crops. The primary concern with blister beetles is they excrete a toxic defensive chemical (cantharidin) that can cause illness and death in livestock and humans.
The toxicity is scary enough, but blister beetles also represent a significant threat to the flowers and vegetables in your garden. You will need to react promptly at the first sign of blister beetles because they are prolific breeders that can quickly grow to unmanageable levels.
Fortunately, for the diligent home-gardener, blister beetles can be removed by hand, but make sure you always wear gloves when dealing with them. Use a container of soapy water to gather the pests, and don't be fooled by a beetle that appears to be dead on the ground. Playing dead is another instinctual survival mechanism for these critters.
Diatomaceous (DT) earth sprinkled around vulnerable plants will help keep the beetles at bay. DT earth will kill beetles as well as turn them away.
Oyster lime shell (OLS) is another treatment to keep the beetles away from plants, but it won't kill them in the process. Sprinkle a layer of OLS on your soil at the start of every growing season as a preventative measure.
If your blister beetle problem is persistent, then a Spinosad chemical treatment may be effective as a last-ditch effort. It's a chemical solution, but at least Spinosad will break down into its harmful components. Try to limit spraying times to the cooler parts of the day, so you can avoid harming the local honey-bee population.
Like many garden pests, the adults pose no risk to the plants, other than to use it for an occasional snack and a breeding ground for their very hungry young.
Longhorn beetles are most common in the Sonoran Desert and prefer less spiny versions of cactus, but they have also been known to visit prickly pears and cholla. A plant with holes filled with a black substance indicates that you have longhorn larvae feasting on the insides of your cactus.
With their fierce-looking mandibles, the adults certainly appear as if they can do some damage to the cactus. They can, but it's minor when compared to the wholesale slaughter the larvae can deliver. Even large cacti can fall prey to the tiny little critters feasting on their insides. Once they are done, there's nothing left of your cactus but a mushy mess.
It's good then that the longhorn beetle has plenty of natural predators, so it only poses a negligible risk to desert gardeners. However, if you have rare or valuable cactus species, you should keep a wary eye out for the pests. They prefer to crawl around on the cactus in the early morning and evenings during summer, so this will be the best time to spot and destroy them before they can lay their eggs.
Not all bugs are harbingers of death and destruction to your garden. There are more than a few helpful species can give you a hand in controlling the harmful varieties, especially if your goal is to use more natural means of pest control.
Hoverflies look like small bees. Like bees, they also help with pollination and enjoy chowing down on aphids.
Parasitic wasps assist with pollination as they hunt for smaller insects like aphids and cabbage worm. What the parasitic wasp does to aphids and cabbage worms to perpetuate its life cycle isn't pretty, but it's better than chemicals, and it's free.
You don't want the dangerous varieties of spiders like black widow and wolf spiders in your yard, but spiders provide a natural solution to pest control. Fortunately, there are plenty of arachnid varieties you can happily co-exist with, such as the daddy-long leg variations, which can help you control population levels of unwanted pests.
You can consider adding a few plant varieties to your garden to attract helpful bugs. The following list will be a good start:
Hopefully, with the above advice, you should be able to control your pest populations without adding harsh chemicals to your local ecology. However, infestations that are hidden away can be tough to spot in time. Try to use the least toxic methods first, but, if all else fails, it’s highly recommended to use a trained professional to get the best results for protecting your garden.
Reference:
[1] https://www.cookcraftcultivate.com/cultivate/common-garden-pests-phoenix/
[2] https://summerwindsnursery.com/blog-az/how-to-protect-your-arizona-plants-from-unwanted-insects
[3] https://www.gardeners.com/how-to/aphid/5315.html
[4] https://www.leafrootfruit.com.au/white-cabbage-moth/
[5] https://homesteadandchill.com/get-rid-of-cabbage-worms/
[6] https://cals.arizona.edu/yavapai/anr/hort/byg/archive/agavesnoutweevil.html
[7] https://www.gardeningchannel.com/how-to-fight-blister-beetles/
