A reader recently sent us a photograph and a message, “This fellow doesn’t quite meet the descriptions of carpet beetle larvae or any of the pantry or clothing moth specimens found on your site. It does look similar to grubs I find in my garden in the spring. It’s quite large at ~1in length and 1/4” diameter. It also looks like it’s defecated in this spot. It was found on the floor just outside of our second closet and near where we store bags of rice. A recent bag of basmati rice was recently purchased. Just last week we reconfigured the closet and did a full cleaning/vacuuming of the area.” Here is the photograph:
We agree with our reader, this specimen isn’t a carpet beetle larva or a pantry moth larva. His guess that it might be a grub is spot on. We believe this is some sort of grub, which means it is the larva of a beetle. To be more specific, we think it might be the larva of a weevil, which is a small beetle that are the pests of crops/stored food items. Based on the information we have, we think the specimen might be the larva of a rice weevil. However, a few things don’t add up.
Rice weevils are stored product pests that attack wheat, rice, maize, and a few other crops. Adults are 2 mm long with brown bodies and a long snout. Female adults lay 2-6 eggs a day. They dig a hole in a grain of rice and lay a single egg inside. The larvae develop inside the egg, hollowing it out while feeding. After a few days they pupate and emerge as adults, and the cycle continues. Therefore, the best way to get rid of rice weevils is to dispose of the infected pantry item.
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There are some details that lead us to believe our reader is indeed dealing with rice weevil larvae. For example, he said the rice was recently purchased and the closet was thoroughly cleaned lately, which suggests that the grub did come from the rice. The grub also has a similar appearance to a rice weevil larva. The problem is the size. Since these larvae develop inside a single grain of rice, they are significantly small. In other words, the one-inch grub doesn’t seem like something that developed in a grain of rice. So, while some clues line up to suggest our reader found a rice weevil grub, we aren’t convinced this is a definite match. It is also possible that this grub came from a different location, and was just near the rice when our reader discovered it. Since our reader only found one grub, we think he should place it outside and investigate the bag of rice. If it shows evidence of a rice weevil infestation, he should dispose of it. If it looks untouched, we don’t think he needs to worry about this grub too much since he only found one!
To conclude, one of our readers discovered a large grub near a bag of basmati rice. We think the specimen bears some resemblance to a rice weevil grub, but we aren’t sure that this is a match because of its large size.