PROBLEM: Shiny or dull hard-bodied insects with tough, leathery wing covers appear on the plants. Each insect's wing covers meet in the middle of its back, forming a straight line down the insect's body. Leaf tissue is chewed, notched, or eaten between the veins, giving the leaves a lacy appearance. The bark may be chewed, or flowers may be eaten. Holes may be found in branches or the trunk.
Many different species of beetle feed on ornamental trees and shrubs. In most cases, both larvae (grubs) and adults feed on the plants, so damage is often severe. The insects spend the winter as grubs inside the plants or in the soil or as adults in bark crevices or in hiding places on the ground. Adult beetles lay eggs on the plants or on the soil during the growing season. Depending on the species, the grubs may feed on foliage, mine inside the leaves, bore into stems or branches, or feed on roots. Beetle damage to leaves rarely kills the plant; grubs feeding inside the wood or underground often kill branches or the whole plant.
SOLUTION: Grubs feeding in the soil or inside plants are difficult to detect and control, so control measures usually focus on the adults. Several different
insecticides, including ones containing carbaryl (SEVIN), may be used to control these pests. Make sure your plant is listed on the label.
Peppermint Soap Spray
This brew is a nightmare-come-true for hard-bodied insects like beetles. The secret weapon: peppermint. It cuts right through a bug's waxy shell, so the soap can get in and work its fatal magic.
2 tbsp. of dishwashing liquid
2 tsp. of peppermint oil
1 gal. of warm water
Mix the dishwashing liquid and water together, then stir in the peppermint oil. Pour the solution into a hand-held sprayer, take aim, and fire! Those beetles will never know what hit them!
You could go to the local store and buy "BAYER Advanced Lawn treatment and Grub Control" or any other grub treatment with "imidacloprid" (the same stuff that is used in flea and tick powders, but much stronger). Pour liberly on the ground near the tree and drip line and till into the soil, then wet the heck out of the soil. The treatment takes about 2 to 3 weeks to work. The chemical is a growth inhibitor and starves the larva.
Bayer Chemical has another product that contains "imidacloprid" and that is "BAYER Tree & Shrub treatment". This can be purchased at any nursery supply or Plant store. It is a bit pricey but is effective