Why are acorns and hickory nuts falling before they’re ripe?
A landowner friend called me recently with a problem.
He told me, “My nuts are going bad.”
After a little clarification, I learned he was talking about the hickory nuts on his property.
That made a lot more sense.
When hickory nuts begin falling early or appear damaged, there can be several possible causes. Sometimes a tree simply produces more nuts than it can support and sheds some of them. In other cases, insects may be responsible.
One insect worth looking for is the nut weevil.
Why hickory nuts may fall before they are mature
If you walk beneath a hickory tree and find a large number of nuts on the ground earlier than expected, that does not automatically mean something is seriously wrong.
A heavily producing tree may drop some nuts simply because it cannot support all of them.
But insect damage is another possibility.
In the case I was looking at, the tree was a shagbark hickory, and there were plenty of nuts already on the ground.
To figure out what was happening, the next step was to open some of those nuts and see what was inside.
How nut weevils damage hickory nuts
A nut weevil can use developing hickory nuts as a place to lay eggs.
The adult female drills into the nut and deposits an egg.
After the egg hatches, the larva begins feeding on the soft material inside the nut.
As the larva continues feeding, it can consume much of the edible portion that would otherwise develop into a healthy hickory nut.
Eventually, the damaged nut falls to the ground.
The nut weevil life cycle
Once the larva has finished feeding inside the nut, it bores its way out.
It then enters the soil, where it digs down several inches and develops into a pupa.
According to the process shown in the video, it may remain underground for two to three years before emerging as an adult.
The adult weevil then makes its way back into the tree and the cycle begins again.
How to check a hickory nut for weevil damage
One clue to look for is a small hole in the nut.
If you find one, crack the nut open.
A healthy hickory nut should contain solid, edible nutmeat.
A damaged nut may be almost empty.
Inside one of the damaged nuts I opened, there was only a small pile of granular material left behind.
That material is called frass.
Frass is essentially insect waste and debris left behind after the larva has fed inside the nut.
Finding frass inside an otherwise empty hickory nut is a strong indication that an insect larva has been feeding there.
What a healthy hickory nut should look like
The difference between a damaged nut and a healthy one can be dramatic.
A healthy hickory nut should contain intact nutmeat inside the shell.
That is what you want to see when you crack one open.
If the interior has been eaten away and replaced by loose, granular material, the nut has likely been damaged by an insect.
Opening several nuts can help you determine whether you are looking at an isolated problem or something affecting a larger portion of the crop.
The same type of problem can affect acorns
Hickory nuts are not the only tree seeds that can be damaged by insects.
Landowners may also notice acorns dropping early.
If you are seeing hickory nuts or acorns falling before you expect them to, insect activity may be one of the contributing factors.
That does not mean every early nut drop is caused by weevils.
The tree may simply be shedding excess nuts.
The best way to learn more is to inspect what is falling.
Pick up several nuts.
Look for small holes.
Crack them open.
Compare damaged nuts with healthy ones.
The evidence inside the shell can tell you quite a bit about what is happening in the tree.
Pay attention to what your property is showing you
Trees, wildlife, insects, and other parts of a property are constantly leaving clues.
Sometimes those clues are obvious.
Sometimes you have to pick up a hickory nut, crack it open, and take a closer look.
If your hickory nuts or acorns seem to be “going bad,” a nut weevil may be part of the reason.
And now you know what to look for.
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