Promoting beneficial insects on your Christmas tree plantation-the first steps

By now you’ve probably read countless articles discussing, and possibly debating, using beneficial insects as part of your IPM (integrated pest management) program. It may seem overwhelming and hard to know where to even begin, but getting started might be easier than you thought.

Over the last 10 years, I have traveled to many growers’ Christmas tree plantations with Chal. We’ve observed a variety of management methods, all mostly successful in their own right. We’ve worked in fields ranging from almost entirely weed free, to unsprayed fields complete with native weeds and grasses, and everything in-between (Figure 1). At these varied sites, we’ve released beneficial insects to test their effectiveness in reducing aphid populations. Through our research trials and observations in these fields, we’ve tallied various populations of beneficials including some of the more widely known lady beetles, their larval stages and egg clusters (Figure 2), hoverflies, lacewings and their very hard to spot larvae and eggs (Figure 3), European honeybees, beetles, spiders, and many more. We learned (after a lot of aphid counting!) that it is not an instant success when using beneficials. So, before you go buy some lace wings or lady beetles to release, you may want to consider some of the ideas outlined below as first steps. If insects have habitats with food, they will more likely stay in that location, if not they’re moving on!

So to get started, here are a few ideas that could make a big impact on your farm. You may even be doing some of them already. The best part is, you don’t need to be an expert or an entomologist to take some initial first steps. We’ve observed many of these concepts in use at farms resulting in higher beneficial counts in many fields. But it was a process that took time.

For any successful endeavor with beneficials, maintaining or creating a suitable habitat is essential for good populations. Insects need food sources of pollen and nectar, shelter, and water. Some primary habitat areas to consider are:

In field edges/fence rows - if your site has areas of native flowering plants that naturally occur, maintain and enhance these areas with additional wild flower seed or other plants where beneficials could feed and find shelter. Additionally, fence rows or other borders can serve as good areas for native shrubs such as Oregon grape and other flowering perennials and annuals (Figure 4).

Remnant ecosystems - many sites I’ve visited have areas of native forests or patches of remaining vegetation surrounding or adjacent to the Christmas tree plantings. These areas not only make great habitat for beneficials but also for birds of prey and bats that assist with controlling other pests such as rodents.

In field plantings - these are areas located within your Christmas tree plantings and can be utilized in various ways. I have seen growers put in wide native grass and perennial strips that double as their spray or roadways with-in their fields. Other methods include end row plantings and covers crops between each row of trees with a native or other low maintenance grass or white Dutch clover (Figure 5).

Slough/wet areas - if your farm has low or poorly draining areas, which tend to be not ideal for growing nobles and/or other species, consider leaving it natural and allowing it to be another area within your farm for added diversity. This can be a good spot for sheltering frogs, attracting birds of prey, and attracting other beneficial insects that may need that specific environment.

Beetle banks- beetle banks are raised swaths four to six feet wide in the fields that are planted with native bunch grasses and provide shelter for overwintering predacious ground beetles. By having these areas, the diversity and number of ground beetles often increases. Ground beetles are known to eat slugs, aphids, and the larvae and pupae of many insects including those of the Douglas-fir needle midge. Other ground dwelling predators, including spiders, benefit from the addition of these grass banks as well.

Utilizing or developing any of these described areas is a positive move towards creating an environment suitable to attract and keep many beneficial insects on your farm. By providing the pollen, nectar, shelter, and places to reproduce and spend the winter for lady beetles, green lace-wings, beetles and other beneficials, you have taken the first step in using beneficials to improve your trees’ quality and possibly using less pes-ticides in the process. Even spraying less herbicide, and having some remaining weeds in your field, provides some essential habitat (Figure 6).

If you are interested in learning more about beneficials, there are lots of resources available online from your local Soil and Water Conservation Districts, through Oregon State University, and many other sources. For your convenience, I have a lot of those resources listed on our OSU Christmas tree website at I hope you will check them out. Promoting beneficial insects on your Christmas tree plantation-the first steps can be found on the OSU Extension Christmas tree website.



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