Knowing your climate zone will help you decide the best time to sow the vegetables, herbs and flowers you want to grow, and which varieties should perform well in your garden. Growing plants that are suited to your climate zone will usually give you the best results in your garden.
The green vegetable bug, or Nezara viridula, is a non-native insect which is common throughout Australia and has a particular fondness for fruit, vegetable and legume crops. Thought to originate in eastern Africa, it now has populations across the globe, and goes under various names including the green stink bug and the green shield bug.
As the names suggest, the adults are bright green, sometimes with lighter spots on the body or head. The adults are roughly 12 to 15mm in length, with a broad, flat, shield shape, and long needle-like mouth parts.
As a gardener and flower lover I was frustrated when I discovered crusader bugs invading the beautiful African corn lily flowers in my backyard. These pests can quickly damage and destroy gorgeous blooms. Fortunately, with some persistence and the right techniques you can get rid of these pesky bugs and restore the health of your African corn lilies.
What Are Crusader Bugs?
Crusader bugs, also known as masked hunters, are a type of insect belonging to the assassin bug family. They are true bugs that pierce their prey and suck out the juices.
These predatory insects prey on a wide variety of pests, including caterpillars, beetles, flies, and aphids. While they may help control some garden pests, crusader bugs will also attack flowers and vegetables Their painful bites can also deter pollinators like bees from visiting your plants
Adult crusader bugs are about 1/2 to 3/4 inches long. They have an elongated, oval shape with a flattened back. Their most distinguishing feature is the “mask” pattern on their head. Coloring ranges from brown to reddish-orange with black markings. Immature nymphs look similar but are smaller and lack wings.
How Do Crusader Bugs Damage African Corn Lilies?
African corn lilies (Ixia species) are prized for their grassy foliage and bright, funnel-shaped blooms that come in colors like yellow, pink, white, and orange. Unfortunately, crusader bugs love munching on the tender flower buds and petals.
The bugs use their piercing mouthparts to stab the flowers and suck out juices and nutrients. This can cause flowers to wilt, turn brown, or fall off altogether. Holes and other deformities will also appear in the blooms. Left unchecked, crusader bugs can strip all the flowers and ruin the display.
In addition to damaged blooms, crusader bugs excrete sticky waste onto the remaining flowers, sometimes causing mold or fungal growth. Their secretions may also attract other pests like aphids.
How to Get Rid of Crusader Bugs on African Corn Lilies
Eliminating these destructive pests will take persistence and patience. Combining multiple control methods is the best approach for protecting your African corn lilies.
Handpick the Bugs
The first line of defense is to manually remove and destroy the bugs. Check plants frequently and crush any crusader bugs you find on the flowers. Dropping them into a bucket of soapy water will finish them off. Pay extra attention during flower bud development when the bugs are most active.
Use a Strong Water Spray
Aim a strong stream of water directly at the bugs to knock them off the plants. Repeat as needed to dislodge any surviving insects. The forceful spray will also wash off any sticky excretions left on the plants.
Apply Insecticidal Soap
Insecticidal soaps provide an organic pesticide that is effective on crusader bugs. The fatty acids disrupt the insect’s cell membranes on contact, causing dehydration and death. Spray African corn lily plants thoroughly, especially new growth, buds, and flowers. Reapply every 7-10 days while the bugs are present. Insecticidal soap won’t harm bees or other beneficial insects.
Use Neem Oil
Extracted from the seeds of the neem tree, neem oil is another natural pesticide option for managing crusader bugs. It contains azadirachtin, which interrupts the life cycle and prevents the bugs from molting and breeding properly. Neem oil also repels the pests. Apply it according to label instructions.
Attract Beneficial Insects
Encourage predators like lady beetles, lacewings, and parasitic wasps which feed on crusader bugs. Planting pollen and nectar sources like dill, fennel, and cosmos will draw them to your garden. Avoid using broad-spectrum insecticides that kill these beneficial species.
Set Up Sticky Traps
Yellow and blue sticky cards can help monitor and control crusader bug populations. The bugs are attracted to the colors and get stuck on the adhesive surface. Place traps near the African corn lilies. Check and replace them regularly to monitor infestations.
Remove Plant Debris
Sanitation is also important. Remove any dead leaves or fallen flower petals where the bugs may be hiding. Cut back plants once flowering is finished. Tilling soil can expose and kill any developing nymphs that drop to the ground.
Use Row Covers
For serious infestations, protect plants with fine mesh fabric row covers. Drape the barriers over metal hoops and seal the edges with stones, landscape staples, or soil. Remove covers when African corn lilies are in bloom to allow pollination.
Rotate Insecticides
Rotating between different insecticide classes helps prevent crusader bugs from developing resistance. For chemical control, rotate between products like pyrethroids, neonicotinoids, and organophosphates. Always follow label directions carefully.
Consider Biological Insecticides
Products containing the bacteria Bacillus thuringiensis (Bt) are effective for controlling caterpillars that eat African corn lily leaves. Since crusader bugs prey on these caterpillars, Bt insecticides may help reduce food sources and populations.
When to Call a Professional
If crusader bugs continue thriving despite your best efforts, don’t hesitate to call in a professional pest control company. They have access to stronger insecticides not available to home gardeners. Professionals can also spot-treat infested plants and target hiding spots that are hard to reach.
Some firms also offer beneficial nematodes that seek out and infect harmful insects. Nematodes pose no risk to plants, pollinators, or people.
Be Persistent for Healthy African Corn Lilies
With their colorful, unique blooms, African corn lilies make a wonderful addition to summer gardens. Don’t let destructive crusader bugs ruin your enjoyment of these exotic flowers. Employing multiple control methods and careful monitoring can help tip the balance in your favor. Your persistence will pay off with vibrant, bountiful blooms.
Dealing with an Infestation
In the first half of the 20th Century, the green vegetable bug was a serious agricultural pest, laying waste to soybean crops in particular. The problem was partially solved by the introduction of a parasitic wasp, Trissolcus basalis, as a biological control agent.
But while the wasp has been effective on commercial scales, a bug infestation in a home garden can still cause serious damage. Manually removing the insects is unlikely to be successful due to weight of numbers, along with the fact that adults are strong flyers and will easily escape, leaving behind only their trademark aroma.
To quell an infestation, two types of spray can be effective.
- For a quick and eco-friendly solution, make up a mix of water, horticultural soap, chilli powder, and garlic. Spray affected plants liberally to suffocate nymphs and drive adults away.
- For a stronger solution, a pyrethrum spray is an organic option. Made from daisy extracts, its highly effective against all sap-sucking insects. However, it will also harm beneficial bugs, so use with care and only when necessary.
An alternative to spraying is to dust infested plants with a derris-based product. This is also organic, made from plant root extracts. But again, it will also kill many beneficial insect species, so use only as a last resort.
How to Use Climate Zones
First, find your climate zone using the map or descriptions below. Next, refer to our sowing chart, which provides approximate sowing times for our most popular seeds for each climate zone.
While knowing your climate zone is helpful when planning your garden, there are many other factors that may affect how your plants grow, including unseasonal weather conditions, the specific microclimate of your garden and how you care for your plants. You know your garden better than us, so if a different climate zone seems to ‘fit’ your garden better, go ahead and use it as a guide.
Our climate zones cover huge areas of Australia, so we recommend gardeners also consider their local conditions when planning what and when to plant. For example, gardeners in alpine areas have shorter growing seasons than gardeners in cool coastal areas, even though both alpine and coastal areas are included in our ‘Cool Temperate’ climate zone. We recommend gardeners in cool regions look at the ‘days to maturity’ information provided for each variety and choose those that will mature in a short (6-12 week) growing season.
- Includes: Darwin, Cairns, Townsville, Exmouth
- High humidity summers with most rainfall in summer and dry, warm winters. Includes northern Australia from Exmouth (WA) across to south of Townsville (Qld).
- Set as my climate My climate
- Includes: Alice Springs, Mildura, Albury-Wodonga, Shepparton, Wagga Wagga, Dubbo
- Hot dry summers, winters can be warm or cool depending on the region. Includes a large area of central Australia from the WA coast to Charleville (Qld), Tamworth (NSW) and Albury-Wodonga (NSW/Vic).
- Set as my climate My climate
- Includes: Brisbane, Bundaberg, Coffs Harbour, Gold Coast, Hervey Bay, Mackay, Rockhampton, Sunshine Coast
- Warm humid summers with high summer rainfall and mild winters. Includes coastal Queensland and northern NSW from north of Mackay to just south of Coffs Harbour.
- Set as my climate My climate
- Includes: Sydney, Perth, Adelaide, Newcastle, Toowoomba, Central Coast NSW, Wollongong, Bunbury
- Moderate humidity and reliable rainfall, with four distinct seasons. Includes coastal areas from north of Port Macquarie to south of Woollongong in NSW, coastal SA and the southeastern coast of WA.
- Set as my climate My climate
- Includes: Melbourne, Canberra, Hobart, Launceston, Ballarat, Bendigo, Geelong, Mt Gambier
- Low humidity with most rainfall in winter; hot dry summers and cold winters. Some regions will experience frosts and snow. Includes coastal areas of south-eastern Australia and alpine areas of Victoria, NSW and Tasmania.
- Set as my climate My climate
What if I can’t find my climate zone? If you can’t locate your zone from looking at the map or the descriptions on this page, we suggest that you think of an area that has a climate that’s similar to yours and use the zone for that area as a guide.
What if I live on the border of two zones? If you live near the border between two zones we suggest you read the descriptions for both zones and decide which best describes the climate where you live. Depending on the microclimate in your garden, you may be able to grow a wider range of plants over a longer season than others in your zone. Lucky you!
What is a microclimate? A microclimate is a small area where the temperature or humidity differs to the climate of the surrounding area. For example, if you live in a climate zone where frosts are common but your garden is protected by buildings or large trees, your garden may be frost-free. Similarly, if you live in a warm temperate zone but your garden is at a high altitude your microclimate may have more in common with the cool temperate zone, so use this as a guide when deciding which zone is relevant to you.
Can I grow varieties not listed for my climate zone? While our climate zones and sowing chart will help you decide what is suitable to plant in your garden, they provide general guidance only. We recommend you start by sowing seed that’s recommended for your climate zone; once you get a few successes under your belt you can experiment with varieties in neighbouring zones and see how you go – gardening is all about experimenting after all!
The green vegetable bug, or Nezara viridula, is a non-native insect which is common throughout Australia and has a particular fondness for fruit, vegetable and legume crops. Thought to originate in eastern Africa, it now has populations across the globe, and goes under various names including the green stink bug and the green shield bug.
As the names suggest, the adults are bright green, sometimes with lighter spots on the body or head. The adults are roughly 12 to 15mm in length, with a broad, flat, shield shape, and long needle-like mouth parts.
Above: Adult Green Vegetable Bug.
Above: Adult Green Vegetable Bug and damaged caused to tomato.
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