The Scolytid beetle is a serious insect pest of young pecan trees. It bores into the tree’s trunk, bark, roots and flower buds, causing damage that can result in the tree’s death if left untreated. Three types of Scolytid beetle exist: bark beetles, wood-boring bark beetles and ambrosia beetles. All are equally destructive small creatures that are brown or black and no larger than 1/3 inch long. Larvae are white, small and legless; they are shaped like a “c” and cause damage to pecan trees along with the adult beetles.
Maintain your pecan tree in good health, because the scolytid beetle takes advantage of trees that are stressed due to lack of water or nutrients. Pecan trees need large quantities of water, so be sure to keep the soil around your tree moist. Newly planted trees need at least 1 gallon of water every day, and after they are two to three years in the ground, they need 1 gallon per day for each year of the tree’s age. If your pecan tree is growing in sandy soil, water it more. The University of Florida advises that preventing this beetle through good tree health is the best cure.
Introduce predatory insects, such as the multicolored Asian lady beetle, stinkbug, lacewing and parasitic flies, which will eat some of the scolytid beetles’ larvae but will not provide complete eradication. The Asian lady beetle also eats aphids and other insects that can bother pecan trees.
Dust trees you suspect of having the scolytid beetle with Bacillus thuringiensis (Bt), a naturally occurring bacterium found in soil. It is known to kill blister beetles, Colorado potato beetles and flea beetles. The website Planet Natural reports that Bt is effective on a “limited range” of beetle species but that it is one of the best controls for this type of pest. The University of Florida reports that Bt is effective against scolytid beetles on mango trees. Bt is most effective when you treat the larvae, or grubs, of bothersome beetles.
Use milky spore on trees that you suspect of having the scolytid beetle. It is a microbe that has been proven effective against the Japanese beetle’s larvae because it infects them, resulting in their death. It is unclear whether milky spore is effective against scolytid beetle larvae, but it is worth a try.
Destroy infected trees by burning or shredding them. Texas A&M University offers this advice. The Asian ambrosia beetle, one of the scolytid type of beetles, causes projections to develop on tree trunks: they resemble toothpicks and usually occur in April or May. Treat nearby unaffected trees with a pesticide such as lindane or Lorsban.