Tent Caterpillars and Aphids on Landscape and Fruit Trees

Three species of tent caterpillar occur in our area: eastern tent caterpillar, forest tent caterpillar, and prairie tent caterpillar.

The eastern and prairie tent caterpillars build tents that are used for shelter or as resting places. Larvae forage during the day in new foliage on nearby branches. Larvae feed for 6 to 8 weeks and are about 2 inches long when mature. Eastern tent larvae are black and rather hairy, with a whitish-yellow stripe down the middle of the back, narrow broken orange stripes on either side of the whitish mid-stripe, and lateral white and blue markings. Prairie tent caterpillar is the most common tent caterpillar species in North Dakota. Larvae are black with a white mid-line stripe broken into dashes, and light blue lateral stripes also broken into dashes.

Forest tent caterpillar utilizes a wide variety of hosts, including ash, aspen, basswood, birch, cottonwood, elm, maple, and oak. Larvae are identified by

keyhole-shaped spots along the midline of the back and by broad bluish lateral bands. Unlike other tent caterpillars, forest tent caterpillar does not form a tent. Instead, larvae gather and spin silken mats on branches. Larvae tend to feed in wandering masses.

Control of all tent caterpillar species should target larvae. Actively feeding larvae are easily controlled with conventional foliar insecticides including acephate, carbaryl, imidacloprid, or any of several pyrethroids. Biorational treatments include Bacillus thuringiensis (Bt) for young larvae, insecticidal soap, and pyrethrin. Boiling water can also be poured directly on tents that contain larvae. Tents may also be physically removed and destroyed. NOTE that the uses of carbayl (Seven) just after flowering may cause apple trees to abort fruit.

A second problem showing up in Traill County is aphids. If aphids are plentiful, the tree leaves are shiny from their excrement called honeydew. This honey dew is mistaken for sap from the trees. We now have a product with the active ingredient “imidacloprid” that is applied at the base of the tree to control aphids and a number of other insects.

When using insecticide, mix and apply according to label directions.

Spring Landscape Problems

Spring lawn, tree, and garden questions are coming into the office. Many questions are common from year to year.

Black knot is a disease of plum, chokecherry, and cherry family. Canadian red cherry trees are very susceptible to this disease. Black knot infects branches and produces a black growth on the branch that extends around the branch and will be several inches in length. The growth shuts off the movement of nutrients and water killing the branch. Eventually Black knot will infect the trunk of the tree, killing the tree. There are no treatments for Black knot. When Black knot infects a tree, prune out the infection a foot before the infection and destroy the branch. Sanitize the pruning shears with 1 part bleach and 9 parts water in-between each cut.

More lawns than usual are exhibiting injury or disease. Necrotic ring spot is being found on some of the lawns. Identification of a specific disease is difficult in lawns and fungicides effectiveness is questionable in many instances. Focusing on cultural practices is my first option when dealing with lawn problems. Dethatching lawns is a common practice but a less utilized practice that is very beneficial is aeration. Aeration is using a mechanical device that will pull plugs from the lawn and allow more air and water to reach the grass roots. Aeration will also help level the lawn if night crawlers are a problem. Proper fertilization of the lawn in the spring and summer also keeps the lawn healthy and more resistant to diseases.

Night crawlers have infected many if not most yards. The worms create bumps in the lawn and make it hard to mow. There are not any treatments that will eliminate night crawlers from a yard. If an insecticide is used and watered into the lawn it might reduce the population but never controls all the night crawlers. Other than the bumps in the lawn night crawlers do not hurt the grass they are just a nuisance.

Creeping Charlie is a ground ivy and is blooming now. Creeping Charlie has small purple flowers and is low to the ground with round ragged leaves. Creeping Charlie is very difficult to control. Spraying during flowering is a good time to implement a spray program using broadleaf weed killers containing dicamba like Trimec. A second application in the fall of the year will help to control this troublesome weed. Unfortunately several years of two applications may be needed to rid your lawn of Creeping Charlie.

NDSU Extension Service/Traill County
114 Caledonia Ave. W.
Mailing Address (Box 730)
Hillsboro, ND 58045
Phone:  701-636-5665   
Fax: 701-636-5666
NDSU.Traill.Extension@ndsu.edu

Office Hours:
8 am - 4:30 pm, Monday-Friday

Summer Office Hours:
(Memorial Day - Labor Day)
7 am - 4:30 pm,  Monday-Thursday
8 am - Noon, Friday

Staff:
Kendall Nichols, Extension Agent/Cropping System
Rachael Hiam, Extension Agent/4-H Youth Development
Leigh Gunkel, Family Nutrition Program Assistant
LeAnn Beck, Administrative Assistant

Related Links:
North Dakota Extension Service
North Dakota Department of Agriculture
Traill County
City of Hillsboro
Cities of Mayville-Portland
City of Hatton