and are usable as a dark ink or wood stain. Industrial Walnut shells are often used as an abrasive in sand blasting or other circumstances where a medium hardness grit is required. The hard black walnut shell is also used commercially in abrasive cleaning, a filtering agent in scrubbers in smoke stacks, cleaning jet engines, cosmetics, and oil well drilling and water filtration. Wood Black walnut is highly prized for its dark-colored, straight grained, true heartwood. It is heavy, strong, shock resistant and yet can be easily split and worked. Along with cedars (Thuja spp.), chestnut (Castanea spp.), and black locust (Robinia pseudoacacia) black walnut is one of the most durable hardwoods in the US. The wood can be kiln dried and holds its shape well after seasoning, which makes this wood even more attractive for wood working. Walnut wood has historically been used for gun stocks, furniture, flooring, paddles, coffins, and a variety of other wood products. Black walnut has a density of 660 kg per cubic meter (41.2 lb/cubic foot), which makes it less dense than oak. Pests Maggots (larvae of Rhagoletis completa and Rhagoletis suavis) in the husk are common, though more a nuisance than a serious problem for amateurs, who may simply remove the affected husk as soon as infestation is noticed. The maggots develop entirely within the husk, thus the quality of the nutmeat is not affected. However, infestations of maggots are undesirable because they make the husk difficult to remove and are unsightly. Maggots can be serious for commercial walnut growers, who tend to use chemical treatments to prevent damage to the crop. Some non-chemical controls also exist, such as removing and disposing of infested nuts. The walnut weevil (Conotrachelus retentus) grows to long as an adult. The adult sucks plant juices through a snout. The eggs are laid in fruits in the spring and summer. Many nuts are lost due to damage from the larvae, which burrow through the nut shell. Black walnut is affected by European canker (Neonectria galligena). The infection spreads slowly but infected trees eventually die. The walnut caterpillar (Datana integerrima) and fall webworm (Hyphantria cunea) are two of the most serious pests, they commonly eat the foliage in midsummer and continue into autumn. Codling moth (Cydia pomonella) larvae eat walnut kernels, as well as apple and pear seeds. Important leaf sucking insects include species of aphids and plant lice