High Quality Photos for Thrips Identification: Rating Phone Attachments.
This is a guest post by Avery Johnson (former OMAFA summer student and current M.Sc. student studying Thrips parvispinus) and S. Jandricic.
Having difficulty identifying thrips on sticky cards and need clear photos to send to your consultant or extension agent? Don’t want to invest in a microscope? Well, you’re in luck, because we’ve done the legwork to find some good alternatives to get high quality photos.
Thrips Identification to Species: Why is this Important?
Recently, thrips species other than western flower thrips have become a significant problem in Ontario greenhouses, likely due to reduced pesticide use, global trade, and other factors.
Specifically, pests like onion thrips (Thrips tabaci), pepper thrips (Thrips parvspinus) and chrysanthemum thrips (Thrips nigropilosus) have been causing significant damage to greenhouse ornamentals in Ontario and beyond. Onion thrips can also be an issue in greenhouse tomato, cannabis and greenhouse strawberries.
Correct identification is the first step to better control, as other thrips species are not controlled by standard biocontrol programs developed for western flower thrips (Frankliniella occidentalis). Knowing this, we developed a simplified thrips identification key for growers, but it requires being able to see small features on the thrips, such as hair patterns.
Extension specialists such as Sarah Jandricic and Cara McCreary at OMAFA often get photos from frazzled growers who are worried they have an usual thrips issue. But specialists and technical reps aren’t able to help unless the photo is of a certain quality.
Why Owning a Microscope is Useful:
We always encourage growers to invest in a good microscope. They really are the “gold standard” for your identification needs, providing high magnification and clear images. As an example of this “gold standard”, you can see a picture we’ve taken of a pepper thrips, below (Fig 2). This photo was taken of the thrips stuck to the thick glue of a sticky card (which was then covered in cling wrap), which makes getting good photos even more of a challenge. But, by taking this photo through the eye-piece of the microscope using a smartphone, you can still easily see the tiny hairs on the pronotum of the insect (circled), which are a key identification feature.
However, your farm may not be willing to invest in a quality microscope quite yet. Further, getting good photos of thrips through a microscope using the camera on your phone can also take a little practice, requiring a steady hand and good lighting. So what are the alternatives?
Alternatives: Camera Phone Attachments
Although smartphones are continuously getting smarter, no smartphone camera currently has the ability to capture the small details necessary for insect identification – even when using a macro setting found on many phone cameras today.
To meet somewhere in the middle between smartphone and microscope, we found and tried out magnifying (or “macro”) lenses that clip-on to any smartphone. Each of these devices were relatively easy to use, at an affordable price, and all available on Amazon. We tested 3 macro lenses with different magnifications (15x, 24x, and one claiming to be 200x) to find the best option. Our goal for each of these attachment lenses was to see if they made identification easier in the field and/or could help with keeping photo records of pests.
The thrips circled in red in the photo below is what we used for all test photos. In all cases, when testing an attachment, we cropped the resulting photo so we could zoom in and compare photo quality and details.
Lens Option #1: CiCiglow 0.45x Wide Angle Lens with 12.5x Macro Lens
This attachment comes with 2 lenses: a wide angle lens that can cover a large field of view and a relatively low-powered macro lens. These can be used separately or together. This is one of the most affordable options, running anywhere from $9-12 CDN on Amazon.ca.
Unfortunately, as you can see from the photo below (Figure 5), even when you zoom in and crop the photo, you can’t see a lot of detail. This makes sense, because the power of this attachment is not that different from a hand-lens you would use in the field.
Even coupled with the phone’s digital zoom, you can’t make out important features like the colour of the eye spots (ocelli) or even really tell what colour the legs are.
Overall, we would stay away from any phone attachments that are less than the magnification of common hand-lenses (e.g. 10-20x).
Lens Option #2: Apexel 12-24X 2-in-1 Macro Lens.
This option is similar to that above, but has 2 macro lenses that can be used together or separately. When used together, they provide more magnification than your typical hand lens. This set will run you around $32 CDN.
The detail on this is objectively better (Figure 6). You can now see the colour of the ocelli on the thrips as well as the colour of the legs. These are important features for some thrips species.
However, let’s face it: the level of detail still isn’t there for the most important identifying feature: the small hairs on the pronotum (or “shoulders”) of the thrips. These hair patterns can help you distinguish most of the thrips species we run across in Ontario greenhouses.
Lens Option #3: 200X Clip On Microscope Magnifier Lens with LED light
Our last contender was brought to our attention by Koen Merkus of Biobest Netherlands. And boy, is it a doozy!
Although I absolutely contest its claim to be 200x magnification (found on high powered, expensive, compound scopes), it IS darn good for a clip on lens. When coupled with the digital zoom on your phone, I would estimate it’s actual magnification to be around 45-50X. It also has an LED light that helps boost the quality of the photos significantly.
Overall, the magnification level, plus the LED light on lens option #3 blew the other lenses away in comparison. The photos taken using this attachment were almost as good as the photo taken through our dissecting microscope at 45X.
The major downside (besides this attachment being more expensive, at around $45 CDN), is that this attachment does require a charge for the LED light to work and we can’t speak to how well it holds a charge yet. It does come with a charging cable, and a little carrying case for both, though.
This particular lens will not produce even low-quality photos if the light isn’t working, as the attachment basically has to sit right on top of the specimen. It therefore isn’t good for live specimens either.
The Final Verdict
Although we always recommend investing in a dissecting microscope, so you can easily examine both dead and live insects at various magnifications, smartphone attachments do offer a viable alternative for identifying dead insects or those stuck on sticky cards. All of the lenses were extremely user friendly and easy to attach to a smartphone, but only option 2 and 3 really produced decent photos needed for insect identification in the greenhouse.
However, only lens 3 really gave enough detail for thrips identification to species, which is important for anyone who grows crops susceptible to Thrips parvispinus and may need to know if they should take immediate action with pesticides or not.
So depending on your specific needs from an attachment like this, you can use our comparison to judge for yourself which of these lenses would work best for you.
Links to the attachments on Amazon:
Lens Option #1: The 12.5X phone lens with 2 in 1 wide angle lens and macro lens
Lens Option #2: The detachable 12-24X 2 in 1 macro lens
Lens Option #3: The 200X Clip On Microscope Magnifier Lens with LED light (Note: if this link doesn’t work, simply search “200x hand lens” in the Amazon.ca search bar, and the same product from a different supplier will likely come right up).
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