Bugs Eating Your Sunflower Leaves

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Last Updated on July 6, 2022 by Marco C.

I love growing sunflowers for a mix of decorative and food needs. But when you get bugs eating your sunflower leaves you suddenly end up with plants that look a bit tatty and also produce lower yields of seed eventually. There are some really neat biocontrols that we can use to reduce this problem. Read on to find out how you can save beneficial insects such as bees while controlling irritating bugs eating your sunflower leaves.

A Quick Overview Of Sunflowers

When we talk about Sunflowers, we typically refer to Helianthus annus – the common sunflower. Sunflowers are members of the daisy family and the Helianthus genus comprises about 50 members concentrated in North and Central America with a few outliers in South America.

The daisy family has a global distribution, and there are many pests globally that are attracted to members of the daisy family. In North and Central America there are many indigenous pests that are also adapted to target sunflowers. What this means is that there are a lot of things that can eat your sunflower plants!! Understanding this allows us to carefully plan how to protect the plants and reduce the impact of pests on them.

The Problem With Pesticides On Sunflowers

One of the big problems with using pesticides on sunflowers is that these plants grow and produce beautiful flowers – the flowers are very attractive to all sorts of bees. Bees are a broad group of pollinators.  We all know the honeybee and the bumblebees – both of which are important pollinators. There are however also many solitary bees, such as leaf cutter, mason, and carpenter bees that are drawn to the flowers too. All of these bees are sensitive to pesticide residues to a lesser or greater degree.

The Problem With Pesticides On Sunflowers

Learn more about: How Much Do Bees Cost


This is a long bit of high-density information approaching – if this sort of logic and reasoning about the use of pesticides worries you, just skip to the next heading. If not, read on – it may change your thinking about our world a bit.

This is a class of pesticides that has grown hugely in popularity globally since the 1990s. The pesticides are absorbed by plants and have systemic activity. This means that you can buy seeds that have been soaked in one of these pesticides. These seeds will germinate and there will be enough pesticide in the plant to protect it for much/all of its growth. The problem is that there is increasing evidence to suggest that these pesticides accumulate in pollen and end up in bees causing damage.

Initial studies concluded little effect was to be had on honeybees for example as shown in this paper from 2001. Around about the same time, bees began to show an accelerated decline in numbers globally, and many beekeepers attributed changes in the behavior of their bees to neonicotinoid pesticides. With time more concrete evidence has been found at a molecular level in bees that shows a definite effect. This is a nice well-conducted paper that actually looks at some pretty powerful aspects of the effect of these residues on brood development in bees.

This is a pretty normal cycle in both pesticides and medicines. Large companies invest huge amounts of money in developing and taking products to markets – these products typically enter the market under patent – the most profitable time for manufacturers to recoup their investment and make a profit. During the initial stages of the market, entry profits are huge and it is possible to fund studies that confirm the initial hypothesis that the chemicals are “safe”. With time, more and more evidence suggests that the products are in fact “unsafe.” They are then removed from the market and replaced with a new “safe” product. This new product will go through the same cycle. DDT is an example of such a cycle, as are things like 2-4-D and more recently glyphosate.

Consequently, with chemical pesticides, my general approach is to apply the precautionary principle – the sale of pesticides is profit-driven, not logic-driven. If I can avoid their use, I will, and I tend to try to find natural agents that mimic natural processes. These may also be bad – but the chances are they will be “less bad” than adding some poorly researched new toxin to my plants.

In Integrated Pest management systems farmers attempt to reduce pesticide use to a minimum and employ various other controls such as biocontrols (parasitic wasps, fungi, and bacteria that attack pests, etc). However, for a small garden, we are lucky! We can often get away with just using biocontrols to stop bugs from eating your sunflower leaves.

Biocontrols To Stop Bugs Eating Your Sunflower Leaves

Biocontrols use natural pathogens and predators of pests to control them. There are a number of stages at which pests can begin eating leaves, and we will now look at how to control the bugs eating your sunflower leaves:

Early-stage: – Cutworms Chopping The Leaves Off At The Ground

Cutworms comprise many species that have this irritating habit of climbing out of the ground at night and eating your plant. It is rather depressing to wake up in the morning and find all your plants flat on the ground, with a chunk of the stem missing, or worse still – just gone.

I find the most effective biocontrol for cutworms is bantam chickens! You can just put a little cage over the area you want to plant, and leave the chickens there for a few days. They will scratch and dig and find all the cutworms and eat them. After they have worked the soil over you can plant your crop and it should make it through without cutworm issues. I tend to let my crops grow up a bit, and then I let chickens in to work the soil later in the season once they cannot damage the crops. This keeps your pest levels down.

If you build a chicken tractor like this it can allow you to move your chickens around and clean up sections of the garden.

Later Stage: – Caterpillars Eating Leaves

There is a big difference between having a large-scale planting and a small-scale planting. When we have tens or hundreds of acres of sunflowers, the methods we can use to control caterpillars are different from that on a small scale. I find that for small plantings of twenty to fifty sunflowers, I actually just walk through the plants and have a look. I carry a little bottle with me, and as I go along I pop caterpillars in the bottle and feed them to my fish and chickens later.

Entomopathogenic Fungi

When it comes to killing bugs eating your sunflower leaves, there is no better punishment to mete out than for the bugs to be digested from the inside by virulent, aggressive, and caterpillar-destroying fungi. Entomopathogenic fungi are nature’s natural balance keepers. These fungi exist as natural controls to keep the balance between plant, insect, and fungus at a sustainable level. Plants make things, insects eat things and fungi run the world. You may not realize this, but fungi control what most of the plants on earth absorb. Fungi in your stomach (mainly yeast) actually control your urges to eat, and fungi can help you heal or die. Fungi are the gentle masters of our planet in a strange way. Sometimes fungi are not so gentle.

I have found in my garden I use a combination of Beauveria bassiana and Metarhizium anisopliae and this mixture of entomopathogenic fungi seems to control the majority of whatever pests used to eat my sunflowers!!

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People often forget that the vast majority of birds feed grubs, worms, maggots, and various insects to their young until they are old enough to be fledged. There are many birds that will also feed their young other foods, but generally, in the war against caterpillars, birds are our best friends. I always try to keep a high population of insect-eating and nesting birds (that eat feed caterpillars to their young) in my garden. This keeps the population of caterpillars to a bare minimum.

There are many off-the-shelf bird nesting sites that you can place around your garden that will attract birds. I just make my own nesting sites, but that is because I live in an area where there are a huge number of bird species that can do this. If you live in North America as my family does,  there is more limited biodiversity and you need to help nature along. These sorts of nesting sites can help.

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Sunflowers are beautiful plants that bring great joy to our lives and gardens. Bugs eating your sunflower leaves damage this joy. I hope that this article has helped you see the most sustainable ways that you can control and manage this problem while enhancing your environment at the same time. We do not need more poisons in our environment, but by harnessing science, nature, and common sense you can control your pest problems in a beautiful way! Share if you found this inspiration.

Read more about: Are Sunflower Leaves Eaten?  


What can I spray on my sunflower leaves?

I would advise against pesticides - sunflowers are pollinated by bees - pesticides kill bees. Spraying poisons on plants that need insects for pollination is a bit silly. I tend to believe that applying biocontrols, such as entomopathogenic fungi (that eat the pests) and encouraging birds to live in your garden (birds eat caterpillars) can provide you with a poison free, healthy environment.

What causes holes in sunflower leaves?

Normally caterpillars. And a few beetles. And small kids with air rifles, stones and catapults. The first two can be controlled with biocontrols. The last are more difficult to control - use reverse psychology on them.

What can I use to stop bugs from eating my plants?

I always work on the precautionary principle. Pesticides are generally bad - we may not find they are bad now, but in ten years time research will show they are. This has happened over and over again. So I use natural biocontrols - entomopathogenic fungi (metarhizium and beauvaria - google them they are on Amazon) and then I keep a high population of birds in myr garden - birds eat caterpillars. So an application of common sense keeps my plants alive - and I do not poison my plants with pesticides that kill the pollinators I need for my plants to make food. It is common sense, but you will be surprised how many people do not get this.

Will sunflowers grow back if eaten?

They will, but their productivity will not be as great as if you amanged your pest problems. If you use a healthy balanced natural range of chickens to clear cutworms in fall and spring, entomopathogenic fungi such as Beauveria and Metarhizium (off the shelf from Amazon), and place bird nesting sites around your garden (birds feed caterpillars to their babies) you can have very happy, healthy plants with no need to use poisons that damage the pollinators you need to get a sunflower crop!

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