A pest is the most destructive when its offspring feed on the plant.
Here is a breakdown of tencommon broccoli pestsand how to get rid of them.
The ants are attracted by the clear, sticky honeydew that the aphids are excreting.
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Aphids are so small that you may only notice them when there is an infestation.
Small numbers of aphids can be washed off with a strong blast from the hose.
If that does not get rid of them, spray the plants withinsecticidal soap.
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Armyworms
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Just as their name suggests, this pest moves in groups.
The caterpillars feed on the crowns of seedlings and skeletonize the leaves of plants.
You might be able to identify older armyworm caterpillars by the characteristic stripe running along their back.
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Small numbers can be handpicked.
For a serious infestation, use products containingBacillus thuringiensis(Bt).
It only works during the larval stage, not on the adult armyworms, which are brown-mottled moths.
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Cabbage loopers eat irregular holes in mostly older leaves and also bore holes in cabbage heads.
Collect them in a bucket of water or treat them withNeem oil.
Young seedlings are the most susceptible, and established, healthy plants are less vulnerable.
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This pest cannot be treated with pesticides, so prevention is your best bet.
Another preventative method is to plant strong, healthy seedlings instead of direct seeding in the garden soil.
They create webs and then feed inside those pockets.
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The recommended treatment of the larvae isBacillus thuringiensisas early as possible.
However, repeated use may lead to webworms developing resistance.
They have black and white stripes across the body and yellow lines along the length on both sides.
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Use floating row covers to prevent the females from laying eggs and the larvae from accessing the plants.
Remove small numbers by hand.
Their light-green color and tapered shape also sets them apart.
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When disturbed, they wiggle back and forth so rapidly that they often drop off the plants.
Rainfall or daily overhead sprinkle irrigation kills the larvae.
Diamond moth caterpillars are often resistant to insecticides including those containingBacillus thuringiensis.
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Flea Beetles
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Cabbage flea beetles are a very persistent pests of broccoli.
Unlike other pests, both the whitish larvae and the adult beetles damage plants.
The adults are easy to recognize, as the small, black beetles jump when you disturb them.
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To treat a flea beetle issue, place row covers over the seedlings until the plants are fully established.
Usingneem oilis usually of short-term effect because flea beetles are highly mobile.
Harlequin Bugs
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Harlequin bugs are shield-shaped insects that resemble stink bugs.
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They are black with bright red, yellow, or orange markings.
The adult bugs are 3/8 inch long.
After the harlequin bugs suck fluids from plant tissue, the damaged areas turn into yellow or white blotches.
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A heavy infestation may lead to the plant wilting, turning brown, and even dying.
The use of insecticides is not recommended against harlequin bugs.Handpick the bugs off your plants.
Adults overwinter on the soil surface under leaves and debris and become active in March or April.
Do a thoroughfall cleanupto break that pest cycle.
Imported Cabbageworms
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While cabbageworm larvae are small, they are voracious.
If their numbers are large, they devour everything but the leaf vein and stems.
In the early stages of the plant, this prevents the formation of a broccoli head.
If a head has already formed, the larvae burrow into it.
Cabbageworms feed on foliage, and if left unchecked often will reduce mature plants to stems.
Thankfully, imported cabbageworms have several natural enemies, including shield bugs and vespid wasps.
Many birds feed on them too.
If those dont keep the numbers in check, useBacillus thuringiensis.
Whiteflies
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In warm temperatures, you might get whiteflies on your broccoli plants.
These sap-sucking insects weaken plants by piercing leaves and stems and feeding on plant nutrients.
As a result, the leaves turn yellow, shrivel, and drop prematurely.
Treatment consists of sticky traps, insecticidal soap, and Neem oil.
Learn More
For more information about growing broccoli, also check out:
Flea Beetles.
Colorado State University Extension.
