As our landscapes come out of their winter hibernation so do the insects that like to feed on our trees and shrubs. Here are five common insect pests that our arborists are looking for in the early spring.

Euonymus scale.
Euonymus Scale. Photo: Edward L. Manigault, Clemson University, Bugwood.org

Euonymus Scale
Crawlers start to hatch in mid to late May. A 2nd generation will hatch out in late July to early August. Foliar treatments that target the newly hatched crawlers is one of the most effective methods to control Euonymus Scale. Soil injected insecticides are also another option.




Scale insect on juniper shrub
Juniper scale. Photo: J.A. Davidson, Univ. Md, College Pk, Bugwood.org

Juniper Scale
Have you noticed any of your juniper shrubs or cedar trees that look off color and unhealthy? Yellow foliage and dying branches could be an indication these plants are infested with juniper scale insects. Examine the poor-looking branches carefully for a small white scale at the base of the needles. Juniper scale can be damaging to junipers when populations reach the point of one scale per needle. Juniper scale crawlers are usually hatched out by early to mid-June, which is when spraying of your trees or shrubs can be done to start to get these insects under control.





Damaged leaves on honeylocust
Adult honeylocust plant bug (right) with late stage nymph of the honeylocust leafhopper(left).
Photo: Whitney Cranshaw, Bugwood.org

Honeylocust Plant Bug or Leafhopper
If the leaves on the ends of your honeylocust tree are twisted, have small white spots, or are turning brown it could be from either honeylocust plant bug or honeylocust leafhopper. Both of these insects hatch out at the same time in the spring; right after the foliage of the honeylocust tree begins to emerge – how convenient! The damage is not usually too stressful, but may be unsightly on younger honeylocust trees. One tree spraying in late May or early June is usually enough to control both of these insect pests.



Caterpillars on pine
European Pine Sawfly larvae. Photo: Steven Katovich, USDA Forest Service, Bugwood.org

European Pine Sawfly
You might find pine sawfly on Scotch pine or Austrian pine, but they are most commonly found on mugo pines. Unlike a lot of spring insect pests, the pine sawfly doesn’t feed on new growth. Instead, they will be found on one-year old needles. Start looking for pine sawfly in early to mid-May. They look like a caterpillar and can be hard to spot when they are small – just remember to check the one-year old needles. They are pretty voracious eaters and it’s not uncommon to see most, or all, of the one-year old needles on a mugo pine consumed by pine sawfly. This gives the plant a thin, spindly appearance. Just about any insecticide will work for controlling pine sawfly, or you can mix up a squirt bottle of dish washing soap and water.




Brown spots on elm leaves
Elm leafminer damage on elm tree. Photo: Whitney Cranshaw, Colorado State Univ., Bugwood.org

Elm Leafminer
Brown patches on the leaves of camperdown elm, English elm or American elm are often caused by the elm leafminer. The adult is a black sawfly. It lays eggs in May and the larvae develop inside elm leaves in late May or early June. There is only one generation per year. Depending on the size and location of the tree, elm leafminer can be controlled with tree spraying, soil injections or trunk injections.



If any of these early-spring pests are infesting your trees or shrubs we can help. The sooner we can get started on controlling these insect pests the less damaging they will be to your valuable landscape plants.





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