I have an unidentified shrub? in the front that is getting hit with small catepillar like bugs. Not sure of the species of eithe the plant or the pests. Have been in the house for 3 years. The first year there was no problem but for the last 2, it has been a hit with these bugs. They eat all the leaves. Last year they were all eaten by July and the place tried to grow they back in August but the bugs attacked them again. This year seems to be similar to last. I’ve tried spraying all of the leaves with a 3-in-1 bug spray on the leaves (top and bottom) to little effect.
There are a number of insects that can cause this damage and at different stages in their development. Some pests attack specific plants while others are not so choosy. It would help if you could identify your shrub. Take a sample of the shrub to your local nursery – ie a section of branch with the leaves that shows not only the type of leaf but the arrangement of the leaves on the branch. If it has flowered in the past, give them a description of the flowers, colour, approximate month of flowering and whether they are scented. Also take a few of the insects in a small jar to help identify them so you get the most appropriate method of dealing with them.
Besides insecticidal sprays which can also harm beneficial insects, some insects can be shaken off or knocked off with direct sprays of water. Insects that like to lay their eggs in the soil around the plant can be stymied with a layer of mulch or landscape fiber so that they cannot lay their eggs for the next generation to attack your plant. If they lay eggs that you can see on the plant, simply squish them off. There are also natural enemies such as predatory mites, nematodes and bacteria. Bacillus thuringiensis (BT) for instance is widely used for controlling several larval insect pests. Note that while it is nontoxic to humans, if it is used to kill pest caterpillars, it can also kill the caterpillars of butterflies.
A plant attacked by pests is a plant under stress. Make sure it is well watered and apply a layer of good compost around the plant. The microbes present in compost will help keep your plant healthy. Fortunately this year we have had ample rainfall so your plant should not be stressed by drought.