What Insecticides Control Dogwood Sawfly Larvae
A group of trees that stands alone and a real show stopper is the dogwood tree, there are more than 50 species of these trees within the dogwood, genus. The dogwood trees range from deciduous temperate trees and evergreens to shrubs. Dogwood trees are native to Europe, eastern Asia, and North America, flowering dogwood can be found in eastern deciduous forests as far as north as Maine, extending west to eastern Texas and Missouri.
Several species are cultivated for their beautiful flowers and then there are a few shrubby species that are grown for their variegated leaves and colorful twigs that come in colors of yellow, red, or purple. The dogwood fruits are food for many wildlife species for example beavers, skunks, deer, wild turkey, black bears, rabbits, foxes, ruffed grouse, chipmunks, bobwhite quail, squirrels, and over 36 species of birds.
However, there’s a garden pest that can reduce the beauty of the dogwood tree known as the dogwood sawfly. This popular insect pest can really cause destruction but with the proper control measures put in place can bring control, restoring the dogwood plant to its former glory. But for this to happen we must first do some investigating to have success.
Dogwood Sawfly Biology
The Dogwood sawfly is a type of non-stinging wasp, this garden pest emerges from May to July and is black and slender with a few small markings that are white. The female has an appendage with teeth like a saw blade which is used to cut slits into the plant leaves where about 100 eggs are laid or deposited. Each egg will cause a small noticeable bump to develop that will eventually turn brown.
Once the eggs hatch the larval stage of the dogwood has the appearance of a caterpillar. The young larvae are white with a yellow belly and begin feeding on the leaves of the dogwood tree. During their development (molting stages) the caterpillar changes colors, textures, and appearance several times. The second larval stage is covered in a white waxy covering and the last larval instar is black and yellow. After the last molt, the caterpillar usually stops feeding and overwinters. In early spring they will pupate and later emerge as adults.
Signs of the Dogwood Sawfly
The young caterpillars will skeletonize (leaves take on a lacey appearance) the plant leaves. These caterpillars usually spend the daylight hours curled up and clinging to the undersides of the plant’s leaves. A dozen or more of these caterpillars can be seen congregating on one leaf when in great numbers the dogwood caterpillar can cause considerable damage (tree defoliation) to the dogwood plant.
While this feeding will not harm the plant’s health it can cause the dogwood tree to look unsightly or unattractive. The older caterpillars eat everything but the midrib. in time caterpillars became a pale cream color with black spots and grow to about an inch long turning yellow and black. Mature caterpillars bore into decaying or softwood and form cells in landscape timbers, logs, and even lawn furniture.
How to Control the Dogwood Sawfly Caterpillar
There are many methods that can be used to control the dogwood sawfly caterpillar, below are a few listed ways that have proven to be effective.
1. The larvae can be hand-picked depending on the amount of infestation and thrown into a bucket of soapy water or they can be squished.
2. If the infestation is heavy then it is better to go with a chemical control method, the use of insecticidal soap, spinosad, or horticultural oil
Caution: When working around dogwood it’s important that you wear long sleeves and a good pair of strong garden working gloves because the leaves of some dogwood species such as blood-twig can cause an itchy rash if skin comes in contact with this plant.
Note: Insecticides tend to be effective against young small, larvae that are half their full-grown size or less. Larvae that are nearing maturity and large aren’t susceptible to insecticides and should be hand-picked and thrown in a bucket or container of soapy water.
Note: Before insecticide applications read and follow the manufacturer’s directions for the best results.
The final word on dogwood sawfly control
Dogwood trees are so beautiful and can really enhance the appearance of a landscape or garden area, to help them to grow their best means we must do our part. The dogwood sawfly can reduce a beautiful dogwood to a nightmare. But with the right control measures we can help our dogwood to bounce back to its glory days. This guide is all you need to do just that as we lend a helping hand in encouraging this flowering beauty to grow their best.
About the author
Norman loves being in the garden, both at home and for his job....
he is 'Natures Little helper' being outdoors, growing his vegetables and flowers from an early age.
Now having spent over 22 years in the profession he want to give some of his knowledge to others...
his vast array of hints and tips you will find scattered over this site will help you no end growing plants in your garden.