Your trusted source for independent, high-quality, science-based advice
© 2025 Berryworld, All Rights Reserved
Mirid bugs cause sporadic and sometimes severe damage to strawberries as they feed with their sucking/piercing mouthparts in the flowers and on the fruit. This damage (fruit catfacing) usually peaks in the late summer, and seems to be variable year by year and location by location.
We have been working on a mirid-control project this summer, in cooperation with two tunnel growers (Ewers in Nelson and The Fresh Berry Company in Hawke’s Bay), funded by SGNZ with significant contributions from the hosting growers.
We set out to test whether a lygus-bug repellent developed by Russell IPM in the UK would work to reduce mirid numbers and damage in strawberries grown in NZ. We also wanted to identify the species of bugs in NZ that damage strawberries by feeding in flowers and fruit. ‘Lygus’ bugs are a family of similar bugs to ‘mirid’ bugs which communicate with similar scent molecules.
“Lybolty” is the brand name of a repellent developed for use in strawberries in the UK, used with three species of Lygus bugs. Lybolty is a pheromone mixture that combines two chemicals used by lygus bugs to attract one another, but in a slightly wonky ratio. Apparently if the ‘perfume’ of a sex attractant is a little off, it is a turn-off to the insects. The scent is deployed in little capsules in a grid-formation in the crop, at 400/ha, replaced every 8 weeks. In the UK, they combine the repellents (a “push”) with the use of an attractant in traps around the crop perimeter (a “pull”) in a system that together can reduce lygus bug establishment in the strawberry crop.
We have been assessing whether the repellents work by counting cat-faced fruit (as a % of total fruit), and by tapping plants to count the bugs themselves. We don’t have an attractant in the system, as we didn’t know what species of bugs we were going to be working with, and it’s very unlikely that an attractant for the UK bugs would attract the NZ species. Attracting insects with pheromones requires a lot more precision than repelling them.
As of the end of February, mirid bugs have not turned up in significant numbers at the two trial locations. Ah, the joys of research, especially researching pest and disease controls. We hope (for research, though not for the growers’ sakes) that the bugs turn up in higher numbers before the end of summer. However, we’re taking away a very interesting learning about pollination. Early on in our trial we were getting high levels of “catfacing” on fruit, despite not finding any mirid bugs in the canopy. One of the varieties had 18% of the fruit damaged! This was a mystery to us at first, since we were expecting bugs to be causing the catfacing. This puzzle has furthered our journey to learn more about strawberry flower pollination biology, which we started to focus on last winter as we struggled with pollination in our indoor winter strawberry crop (https://berryworldnz.wordpress.com/2024/10/05/knobbly-berries/)
We believe this high level of catfacing we saw in the trial early on was due to pollination troubles rather than bug feeding. However, we don’t know whether the pollination troubles are due to temperature extremes (either hot or cold), or lack of pollen movement.
Mirid bug identification: second goal of the project
It turns out that the species that will feed on strawberries are varied in NZ. The MPI lab in Christchurch has been doing the identifications for us, and there haven’t been many double-ups, which makes me think we probably have more species to identify yet.
You could help us with this part of the project!
If you have bugs feeding in your strawberries, please contact Molly Shaw at Berryworld to organize a sample for identification. We’re particularly short on north island samples at this point.