Spruce Needle Miner

Article written by: http://umanitoba.ca/faculties/afs/hort_inquiries/835.html
Photo by: www.missouribotanicalgarden.org


Problem type: Insect
Name of problem: Spruce Needle Miner
Plant name(s): White, Engelmann, Norway and Colorado blue spruce
Symptoms / Characteristics:
Needles are hollowed, severed and woven together with silk webbing. These nests of dead needles and webbing are typically located at the base of large branches.

Defoliation is due to larvae of the moth Endothenia albolineana. The adults emerge during May and June at which time the females lay eggs along the base of needles. When the larvae hatch, they bore into the base and tunnel their way up to the tip, feeding on the interior. Initially the larvae feed on one side only, but consume more of the interior as they mature. A mass of dead needles and frass (droppings) becomes a nest in which the larvae overwinter. The nests also trap dust and airborne debris, which impairs vigour, and decreases aesthetic value of the plant. Defoliation weakens the tree and renders it susceptible to secondary insect and disease pests. Prolonged infestation may eventually kill the tree.

The larvae are green with dark brown heads, and may reach a mature length of 8 mm. The adults are grey and brown moths with three irregular bands of white on their forewings. Other species of needle miner have been known to attack spruce, pine and fir trees.

Control / Preventions:
A high pressure garden hose can be used to wash away nests before bud break in the spring. Fallen nests must then be collected and burned. However, this method may not fully eliminate an infestation. Pruning heavily infested areas may also be required. Dimethoate may be used as a chemical control in accordance with manufacturer directions and precautions.

Pest Management (IPM)

Integrated Pest Management is a strategic plan that uses a variety of techniques, either alone or together, to prevent and manage pests.

There are 4 methods by which we can attempt to accomplish this.

1. Cultural- some of these are: rotating crops, proper spacing and location of plants, watering plants early in the day and giving them the needed amount, applying fertilizers correctly and at proper times of the plants growth, and by choosing resistance varieties and cultivars.
2. Physical- hosing off insects with forceful stream of water, picking off insects by hand, pruning dead and diseased plant parts, cleaning up leaf litter (especially if you suspect any diseases in it).
3. Biological – encouraging natural predators such as birds and ladybeetles.
4. Chemical- use only as a last resort. Use the correct chemical, apply it correctly and only to areas where needed. If repeated treatments are necessary, rotate the chemical with one that has a different mode of action, to reduce resistance. Eg.- how it affects the plant or insect.

By routinely inspecting your plants, you can often detect problems early, before the plant becomes stressed. (A stressed plant, such as one that is over/under watered or not in its favorable environment, is an easy target for more severe problems.)  You can use the first three options before things become serious enough to resort to chemicals. It takes a little research to identify the plants you have, the problems that are associated with those plants, and to identify the signs and symptoms of invasion; but it is a lot better to prevent the problem than to implement the cure. Your plants and the environment will appreciate
Photo of aphids:utahpests.usu.edu.