These are cut logs that were used for shiitake mushroom cultivation for 3-5 years. They are domestic Konara oak logs. They are crumbly, but how about using them for insect breeding? As shown in the photos, there are variations in size (diameter, length), the extent of mycelial growth, and individual differences. They have been dried in the sun for several days before being put up for sale. Insects may be present. If you are concerned, please heat treat before use. *We offer a mix of non-standard items (blackened cut surfaces, insect marks, crumbling, no bark, etc.) ◯Size Length: Approximately 14 cm to 15 cm Diameter: Approximately 7 cm to 7.5 cm 19 pieces per set ◯Hardness Soft enough that a toothpick can be inserted, such as near the bark. *These are shiitake mushroom cultivation logs, and the mycelia have grown well even between the bark, and they are well-decayed. *Can also be used as food for larvae of beetles, etc. *Some people use them as perches for adult insects. ◯Notes *Because the wood is fully ripe, some parts of the product may be easily broken, so please handle with care after receiving it. *Occasionally, Quercus serrata wood may be mixed in. *Since they have not been treated for insects, please heat treat them before use if you are concerned. *Due to the nature of the product, changes in size and texture, cracking, peeling of bark, and the appearance of mold and moss may occur over time. *Shipped via anonymous delivery. *This is a personal sale, not a business. I cannot answer specialized questions. Please refrain from purchasing if you are looking for perfection. Please purchase only if you agree to the above. Please ask if you have any questions.