How to get rid of thrips

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For the best results, tape & cards should be placed just above the crop canopy – this may mean periodically moving the traps khổng lồ maintain optimal positioning.

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April 12, 2017 By Dr. Sarah Jandricic


Petal streaking caused by thrips feeding, which makes the plant unsellable.

May 2017 – In Ontario, we continue khổng lồ struggle with control of western flower thrips. Even those growers religiously using preventive, mite-based biocontrol programs can suddenly find themselves throwing out a significant portion of their crop due lớn visible damage.

Why does this happen? It’s hard to lớn know for sure sometimes. But things lượt thích higher than usual numbers of thrips eggs in imported cuttings, hot dry weather (like we had this summer), or problems with mite sachets (such as unique issues or improper placement) can all lead khổng lồ high thrips populations.

What is clear is that more than just predatory mites are needed to lớn keep your biocontrol program consistent and stable. & one of the easiest and cheapest ways to bởi this is with mass trapping.


Mass trapping often consists of large sticky cards or long ribbons of sticky tape that attract and trap pests. Sticky traps can remove large numbers of adult thrips by intercepting them whenever they decide khổng lồ fly – whether that’s when they first venture into your greenhouse, when they’re disturbed, or when they just decide to kiểm tra out some plants on the next bench.

I can already hear some of you saying “But tape is messy and my workers hate it.” I get it – I do. But I’m still going lớn tell you that mass trapping is worth every bit of annoyance it causes in terms of its contribution lớn thrips management. Remember, each thrips female can lay over 300 eggs her lifetime1, so removing any number of adults lightens the load on your biocontrol program.

Several studies demonstrate that using mass trapping effectively reduces the number of thrips in horticultural crops. One of the best examples is in strawberries produced under plastic. Here, the number of thrips averaged 6/flower with the existing IPM program (predatory mites, spinosad sprays), but dropped khổng lồ 2. This corresponded khổng lồ far lower thrips damage on fruit and increased grower returns.


My own research this past summer showed the staggering numbers of thrips mass trapping can remove from floriculture greenhouses in Ontario.

In trials testing different colors và patterns of tape in commercial mum crops (both potted and cut;, the best treatment caught an average of > 150 thrips/2 feet of tape every week (see Fig. 4C).

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In just our small trial plots, we caught over 10,000 thrips from June to August.

Now, If we calculate this out to see how many thrips we could have removed over the summer if we’d put tape down all the post rows in a whole greenhouse compartment, we get over one million adult thrips. This is one million fewer thrips reproducing in your crop; one million fewer thrips causing feeding damage; và one million fewer thrips overwhelming your predatory mites.

It just makes sense that if you’re going khổng lồ set up mass trapping, you might as well get the best bang for your buck. So which is the trap type is the most attractive khổng lồ thrips?

We often hear that xanh traps a) catch as many (or more!) thrips than yellow traps, và that b) xanh traps will catch fewer flying biological control agents, helping preserve your bio programs for other pests. And now there’s new, patterned blue tape on the market that purports lớn catch even more thrips. But is any of this actually true in practice? Given that the scientific literature is all over the place on this one, I thought it was important to test this in Ontario greenhouses. Along with trials last summer, I tested this in preliminary trials this spring.

Test plots were mix up in a commercial potted chrysanthemum operation and thrips catches on different traps were tracked over time. Studies indicate the specific hue of a trap (i.e. Wavelength of light it reflects) is critical in thrips attraction, so it was important to thử nghiệm traps from multiple suppliers.

We also looked at beneficials trapped, as this greenhouse has active banker plants of A. Colemani and regularly releases Diglyphus và Atheta.

For two out of the three trap products, yellow caught more thrips – a LOT more thrips (Figs. 4A và C). Catches averaged from more than two-times more thrips on yellow vs. Blue, khổng lồ up to eight-times more thrips. However, with a third manufacturer, xanh was actually better than yellow (Fig. 4B), but only slightly. Patterned xanh tape wasn’t any better than regular xanh tape in our tests (Fig. 4C).

Although yellow cards from multiple manufacturers caught more beneficials on average (Fig. 5A & B), the numbers were very low (

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