What you see: A white something or other on the frilly end of a blueberry. It’s not fuzzy like mold and may look like linen or gauze up close.
What it is: Possible spider webbing!
Eat or toss: Probably toss. Unless you like eating bits of spider webs. There’s not really enough berry left to salvage. But this is pretty cool, right?
At first, I assumed the white bit atop this blueberry was mold. But fortunately for me, around the time I encountered it, I had been emailing with Matt Bertone, a diagnostic entomologist at the North Carolina State University Plant Disease and Insect Clinic, about various ways spiders leave webbing on our food (like this apple).
And it turns out this berry isn’t afflicted with mold, but rather is sporting something that was probably spun by a spider. Bertone said the spiders are more likely to inhabit produce like this berry when it’s still in the field rather than after harvest. Back on the blueberry bush, the spider would have used the star-shaped area where the flower used to be as a protective nook for sleeping or for laying eggs. It might have encased the eggs in some webbing and gone on its way.
Can you find spiders inside blueberries like this?
By the time the blueberry arrived in my house, odds were good that any baby spiders had hatched and fled. But, I was curious. So I used a toothpick to gently pry things open and found only some clingy, cottony wisps. But, Bertone kindly shared images he captured of baby spiders tucked inside a blueberry. Check them out below, and if you do your own investigations, make sure to have a magnifying glass handy!
Mold vs. spider silk on blueberries
So how can you tell the difference between mold and spider silk on blueberries? Well, first, consider the location. Mold likes wounds and the area where the stem used to connect because it’s weaker and more likely to have an opening where the mold can slurp up some moisture and dig into nutrients in busted blueberry cells. A spider, on the other hand, is more likely to set up shop in the indentation just under the frilly spot where the flower used to be. That nook offers protection for tiny spiders.
A white mold on blueberries will also likely look fuzzy or at least a little fluffy and will visibly degrade the blueberry and spread to other blueberries over time. Webbing from a spider on the other hand, may look like gauze or loosely knit linen and won’t destroy the berry or spread to other berries. Of course, as berries age they will naturally shrink and wrinkle with water loss.
For more on berries, including more about that white film you sometimes see on the surface of blueberries, head to the EatOrToss Berry Library.
SOURCES:
- Matt Bertone, PhD. Entomologist. Director, Plant Disease and Insect Clinic. North Carolina State University. Email correspondence. Spring 2025.
- White wispy spots on blueberries. Rachael Jackson. EatOrToss.com. May 30, 2023.
Or should we say, LiBERRY. No, we probably shouldn’t. But we still did.
