Lindorus Kicks Christmas Trees Off Pesticide Treadmill

Lindorus eating pine needle scale

Lindorus eating pine needle scale

After years of spraying more pesticides and achieving less control, many of Ron Evans’ Christmas trees were left unfit to sell because of messy scale infestations. Farming for over 45 years, they began noticing pine needle scale 15 years ago. Scotch pine, red pine and Austrian pine were especially susceptible. In the mid 1990’s they used conventional pesticide spray based on monitoring and treating hot spots. Despite treatments, the scale crawlers spread and all trees with scale were eventually sprayed twice a year.

Within six years Evans reported, “Typically we were spraying all the fields three to four times per year. We tried to follow the recommendations found in pest control literature, but still found ourselves fighting a losing battle. Most of the literature recommends spraying scale when crawlers are present. Scale typically crawls for three days after hatching, and we logged as many as seven hatches the summer of 2000. The logistics of spraying 100,000+ trees in a three day window, three to four or more times per year became more than a nightmare.” Four E’s Trees was burning 1,500-3,000 trees every year that were ruined by scale pests. 

Evans called the University of Illinois Department of Entomology. Among their suggestions was a small black lady beetle Lindorus lopanthae as a scale predator. Ready to try something new, Evans cooperated in a test of Lindorus beetles. He put a small number of Lindorus in a remote patch on his farm during June 2002, while continuing with his conventional program everywhere else. In November, while they were harvesting (with difficulty because of scale damage), he walked back to the remote field, where five months prior he had released the Lindorus beetles and forgotten about them. To his surprise this patch of trees was the only area on the entire farm without a scale infestation!

Four E’s Trees released several thousand Lindorus beetles the following season. According to Evans, “The first year results were amazing. We had entire fields of marketable size trees that we could not sell in the 2002 Christmas season due to excessive infestations of scale. These same fields were scale free, healthy and salable for the 2003 season. In addition to reducing the scale infestations to manageable levels, we spent $3,000 less on pesticides and countless fewer man-hours with the Lindorus beetles than the spray program the previous year.” Lindorus must be released annually when there are enough scale to feed them, which is usually late spring to early summer.

In 2005 Rincon-Vitova Insectaries, recognizing that Four E’s was able to provide valuable technical support to expand the successful use of one of the organisms it grows, offered a dealership to Four E’s Trees to sell Lindorus to the Christmas tree industry. Evans writes and speaks to Christmas tree associations and supplies Lindorus to over 50 growers in 14 states. Four E’s helps customers assess the scope of the problem, the type of scale, the number of beetles needed and timing of release, other cultural practices to produce pest resistant trees, how to distribute the beetles and monitor results. Beetles are shipped overnight to Four E’s customers for them to make the releases. For more information about Lindorus for scale in Christmas trees, write to Ron Evans <FourEsTrees @> or call (217) 864-4704 and ask for Ron or Doug.


4 Responses to “Lindorus Kicks Christmas Trees Off Pesticide Treadmill”

  1. 1 kate field September 26, 2009 at 6:20 pm

    What was the timing of Lindorus release? Crawlers in about April? Are Lindorus hardy over zone 5 winter? I am in Wisconsin not far away and would like to experiment with Lindorus on landscape pines.

  2. 2 Ron Evans October 2, 2009 at 12:34 pm


    Depending on where you are located in Wisconsin, I would estimate a mid to late May release would be better. Typically in central Illinois, I target the first week of May for my releases. What types of scale are you trying to control? Lindorus will not survive a zone 5 winter. Ideal release times target scale hatch and the crawler stage of their life cycle. We try to time our releases so that night time temperatures do not fall below 40 degrees F. I have seen Lindorus survive a 28 degree night, but don’t think they will survive much colder than that.

  3. 3 Steve Alm October 16, 2009 at 4:59 pm

    Will Lindorus work on elongate hemlock scale in Rhode Island? When would be the best time to apply them? How many per acre?

  4. 4 Jan October 17, 2009 at 6:48 am

    A report in the Florida Entomologist is very encouraging about augmentation with Lindorus for control of elongate hemlock scale (EHS). [] It was the most dominant of six naturally occurring predators in forests in Tennessee and North Carolina.

    As Ron suggests above, make releases early in the season as soon as night temperatures remain above about 40′ F. Numbers depend on host density and distribution of the scale. The predator is very reproductive on scale crawlers, so putting 10 to 40 beetles per hotspot can become a greatly expanding population spreading through the forest for the rest of the season if no harm is done with pesticides. A trial in a block like Ron Evans did for pine scale and pine needle scale is the only way to develop a protocol. (Be mindful of the interference from ants as well as pesticides.)

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