What nuts have parasites? Unpacking the truth about nut infestations

November 29, 2025 •

4 min read

According to agricultural studies, the 'parasites' people report finding in nuts are almost always the larvae of common insect pests, not true parasites. Dispelling this myth is important, as understanding what nuts have parasites in the form of these bugs helps ensure proper handling and storage for a safer eating experience.

Quick Summary

The fear of finding parasites in nuts is based on a misunderstanding of common insect infestations, with pests like the navel orangeworm being the true culprits. Modern processing methods and proper consumer storage ensure that nuts are safe to eat, with roasting effectively eliminating any potential larvae.

Key Points

Not Parasites, but Pests: The 'parasites' found in nuts are actually insect larvae, most commonly from moths or beetles, and are not a threat to human health in the way true parasites are.
Processing Eliminates Risk: Roasting or other pasteurization methods used in commercial nut processing effectively kill any insects, eggs, or larvae, making processed nuts very safe.
Proper Storage is Key: To prevent new infestations of pantry pests, store nuts in sealed, airtight containers in a cool, dark place or the refrigerator/freezer.
Vigilance with Raw Nuts: Raw nuts from bulk bins or less regulated sources carry a slightly higher, though still low, risk of undetected infestation and should be inspected and properly stored immediately.
Industry Standards Protect Consumers: A combination of good agricultural practices in orchards and strict sorting procedures in processing plants prevents most infestations from reaching the consumer.

Debunking the Parasite Myth: The Real Culprits

The widespread belief that nuts can harbor animal-based parasites is a significant misconception. In reality, the issue is typically a matter of insect infestation, where larvae from moths or beetles may enter and contaminate the nutmeat. While the thought of finding a tiny worm in your snack is off-putting, these are not the same organisms that cause human parasitic diseases. Understanding this distinction is crucial for both consumer education and food safety, and it highlights the importance of proper agricultural and processing controls.

Common Nut Pests and Their Targets

Several insects are known to infest nut crops at various stages of growth and storage. The susceptibility of a nut depends largely on its shell integrity and the environmental conditions it experiences before it reaches the consumer.

Navel Orangeworm (Amyelois transitella): This is one of the most damaging caterpillar pests in tree nut orchards, particularly for pistachios, almonds, and walnuts. The moth lays its eggs in developing nuts, especially those that have already split their hulls. The larvae then bore into the kernel, leaving behind webbing and waste.
Peach Twig Borer (Anarsia lineatella): While primarily known for affecting peaches, this insect can also infest almonds. The larvae can enter the shell in the field and feed on the surface of the nutmeat.
Warehouse Beetle (Trogoderma variabile): This dermestid beetle is a notorious pest of stored products, including pistachios. Infestations typically occur post-harvest in storage facilities.
Filbertworm (Cydia latiferreanus): This pest is a major problem for walnuts and hazelnuts (filberts), where the larva feeds inside the shell.
Other Storage Pests: Nuts, particularly those stored for long periods, can be affected by other common pantry pests like the almond moth or drugstore beetle.

The Role of Processing and Food Safety

The nut industry has established robust food safety protocols to prevent and mitigate pest contamination. This is why finding infested nuts in modern, commercially processed products is rare. The most effective methods include:

Pasteurization/Roasting: The heat from roasting, or other pasteurization techniques, effectively kills any insect larvae or eggs that may have made it past initial sorting. This process makes roasted and pasteurized nuts exceptionally safe.
Sorting and Inspection: At the processing plant, nuts undergo a rigorous sorting process. Automated systems, visual inspections, and even floating processes are used to separate and discard any damaged or compromised nuts before they are packaged.
Controlled Atmosphere Treatment: For some products, particularly those sold raw, processors may use controlled atmosphere or heat treatments in storage facilities to eliminate pests without affecting the raw state of the nut.
Pest Management in Orchards: Good agricultural practices (GAPs) are used in orchards to control pest populations from the start, minimizing the chances of infestation in the field.

Protecting Your Nuts at Home

Once you bring nuts home, it's up to you to maintain their safety and quality. Proper storage is the most important step in preventing any potential infestation from pantry pests.

Always inspect before buying. For bulk bins, give the nuts a quick look. Are there any broken pieces, powdery residues, or tiny holes that indicate a problem? It’s often best to buy from a reputable store with high product turnover.
Store in airtight containers. Transfer nuts from their original packaging into a sealed, airtight container as soon as possible. Glass jars or heavy-duty plastic containers work best.
Choose a cool, dry place. Nuts contain oils that can go rancid. Storing them in a cool, dry, and dark pantry or even the refrigerator or freezer will extend their shelf life and deter pests.
For raw nuts, consider freezing. If you are concerned about purchasing raw nuts, placing them in the freezer for 48 hours can kill any potential insect larvae before storing them elsewhere.

Comparison: Raw vs. Processed Nuts

To better understand the risks, consider this comparison between different types of nut products.


Feature	Raw Nuts	Processed/Roasted Nuts
Pest Risk	Slightly higher risk if not properly stored, as larvae could potentially hatch.	Very low risk due to heat treatment eliminating potential pests during roasting.
Storage	Highly sensitive to heat and moisture. Best stored in an airtight container in the refrigerator or freezer to prevent rancidity and pests.	More shelf-stable, but still benefits from cool, dry, airtight storage to preserve freshness.
Shelf Life	Generally shorter than roasted nuts due to delicate oils.	Extended shelf life due to heat treatment stabilizing oils and removing moisture.
Taste	Earthier, more natural flavor profiles that can be more subtle.	Richer, deeper flavor and aroma developed during the roasting process.
Nutritional Profile	Contains more active enzymes and heat-sensitive nutrients, but the difference is generally minimal.	Minimal changes to the core nutritional profile, with some antioxidants potentially affected by high heat.

Conclusion

The concern over what nuts have parasites is rooted in the occasional, and unpleasant, reality of insect infestations. However, it is a problem that has been largely mitigated by modern agricultural practices, stringent processing controls, and proper storage. The larvae of insects like the navel orangeworm or warehouse beetle are the true issue, not true parasites. For the consumer, purchasing from trusted sources and following simple, airtight storage practices is the best way to ensure the safety and quality of your nuts. Ultimately, this knowledge should not detract from enjoying nuts, but rather provide reassurance that any risks are both manageable and minimal. For more information on food safety standards, consult official sources such as the U.S. Food and Drug Administration's guidelines for nut products.

For more information, visit the U.S. Food and Drug Administration's guidance on nuts.

Frequently Asked Questions

While the experience is unpleasant, eating a nut with an insect larvae is unlikely to make you sick with a parasitic disease. The primary concern is potential foodborne bacteria or toxins from fungal contamination, which is rare in properly handled nuts.

Yes, roasting is a highly effective method for killing insect larvae, eggs, or any other pests that may be in nuts. The heat treatment makes commercially roasted nuts extremely safe from this type of contamination.

Bulk bin nuts can have a higher risk of secondary infestation from common pantry pests if not stored, rotated, or handled correctly in the store. Proper storage by the consumer is especially important for these products.

For optimal safety and freshness, store nuts in a sealed, airtight container, like a glass jar, and keep it in a cool, dry, dark pantry or, for longer-term storage, in the refrigerator or freezer.

Look for small, pinhole-sized entry points on the shell, fine webbing on the nutmeat, and powdery residue, known as frass, which is insect waste. A rancid or off smell can also be a sign of poor quality.

Tree nuts like almonds, pistachios, and walnuts are known to be susceptible to certain pests, such as the navel orangeworm, which can enter through hull cracks. Peanuts are also vulnerable to mold and stored-product insects after shelling.

Yes, freezing raw nuts for at least 48 hours is an excellent way to kill any potential insect larvae and prevent future pest development without affecting the nut's quality. After freezing, you can store them safely in the refrigerator or pantry.