Thrips: Understanding the Pest

This week we’re taking a look at the commonly called “Thunder Fly”. These tiny insects are actually called Thrips and are black in colour and narrow with hairy wings measuring around 1.5mm.

Thunder Flies

Thrips are largely an agricultural pest which is why Herefordshire and Worcestershire residents often report problems with Thunder Flies as our rural county has vast amounts of fields and agricultural properties.

So how do these insects cause problems in residential properties and business premises?

Well, they have been known to collect in significant numbers inside smoke detectors and this can trigger fire alarms to go off.

Thrips feed on plant sap and on hot and humid days they congregate on window sills in large numbers.

With climatic changes, these insects become more of a problem and can get into clothing and hair. This is largely a nuisance pest however and a small thrip infestation can normally be dealt with easily by the householder simply removing them from the property.

However, a significant infestation of thunder flies would better be solved by a professional pest controller who has access to professional treatments to solve pest problems.

Thrips Biology & Lifecycle

Understanding how thrips develop is key to stopping infestations before they bloom.

Egg-Laying Habits & Host Preference

- Thrips lay eggs inside leaf tissue or within flower buds, making detection tricky.

- Preferred hosts include tomatoes, cucumbers, chrysanthemums, and fuchsias, especially in warm, protected environments.

- Eggs hatch in 2–7 days, depending on temperature.

Nymph Stages & Development Timeline

- Nymphs go through 2 instars (growth stages) before dropping into soil or leaf litter to pupate.

- They resemble adults but lack wings—often pale yellow or green.

- Total lifecycle from egg to adult takes 7–14 days in summer, faster in warm, dry conditions.

Seasonal Activity in the UK

- Peak thrips activity typically spans May to September, with spikes during prolonged dry spells.

- Warm greenhouses, conservatories, and polytunnels can sustain populations year-round.

- Early symptoms (leaf silvering, flower damage) often appear mid-May.

Thrips thrive when summer skies stay dry!

Overwintering Behaviour & Survival

- Thrips overwinter in soil, mulch, leaf litter, or tucked within greenhouse structures.

- Some species can survive in unheated indoor environments, re-emerging with spring warmth.

- Cleaning up plant debris and controlling indoor conditions helps interrupt their cycle.

Monitoring & Identification of Thrips

Early detection is the key to managing thrips before damage spreads. Here's how to keep an eye on these elusive pests:

Colour Traps & Visual Tools

- Sticky Traps: Hang yellow or blue traps near susceptible plants. Yellow is great for general attraction; blue is especially effective for Western Flower Thrips.

- Magnification Aids: Use a pocket magnifier or loupe (x10–x15) to inspect undersides of leaves, buds, and flower crevices where thrips often hide.

Behavioural Cues

- Erratic Movement: Unlike aphids or mites, thrips twitch and scuttle rapidly when disturbed.

- Hiding in Blooms: Pay close attention to tightly packed petals—thrips love to burrow inside flowering heads.

- Silvering & Flecking: These visual symptoms often precede visible insect presence—consider them an early red flag.

DIY Thrips Monitoring Checklist

For weekly use during the growing season (May–Sept):

✅ Check underside of leaves using magnifier.

✅ Inspect flower buds and blooms for hidden thrips.

✅ Note silvering, flecking, distorted growth.

✅ Replace sticky traps every 1–2 weeks.

✅ Record sightings and symptom locations.

✅ Isolate any suspicious plants for further monitoring.

Pest Pro Tip:

Turn this checklist into a laminated card or downloadable PDF for greenhouse or allotment use.

Climate Change & Environmental Considerations

Thrips may be tiny, but their behaviour is shaped by global shifts.

Climate Impact on Thrips Populations

- Hotter summers and prolonged dry spells accelerate thrips breeding cycles and spread.

- Warmer winters mean fewer die-offs, allowing populations to rebound more aggressively in spring.

- Greenhouses and indoor plant areas are particularly vulnerable during extreme heat events.

If you’ve noticed more thrips year-on-year…you’re not imagining it.

Eco-Friendly Alternatives to Chemical Control

- Use biological predators like Orius insidiosus (minute pirate bug) or Amblyseius cucumeris (predatory mite).

- Spray neem oil, insecticidal soap, or homemade garlic-chilli sprays to deter feeding.

- Companion planting (e.g. basil near tomato) can confuse or repel thrips naturally.

- Growers are shifting toward IPM strategies that blend natural controls with observation.

Neonicotinoid Risks to Pollinators

- Common thrips-targeting insecticides like acetamiprid and imidacloprid (neonics) pose risks to bees, hoverflies, and butterflies.

- Residues can accumulate in nectar and pollen, affecting non-target insects.

- The UK restricts some neonics under pollinator protection schemes—but vigilance is key.

Be kind to pollinators—choose selective, low-toxicity treatments.

There are several reasons why people should hire a pest control company to get rid of thrips:

Expertise: Pest control companies, like us, have trained professionals who have the knowledge and experience to effectively identify and control thrips infestations. A qualified pest controller will be able to determine the severity of the infestation, the type of thrips present and develop a plan to address the infestation.

Safety: Pest control companies use professional-grade pesticides and equipment that are not available to the general public. These products are specially formulated to target specific pests and are applied by trained professionals who know how to handle them safely.

Efficiency: Registered pest control companies have access to a wide range of tools and techniques to quickly and effectively eliminate thrips infestations. They may use different type of pesticides, integrate pest management techniques, and use equipment that is specifically designed for thrips control.

Cost-effective: Hiring a pest control company can save you money in the long run. They will be able to quickly and effectively eliminate the infestation, reducing the need for repeated treatments and minimising crop damage.

Monitoring: A pest control company will also monitor the infestation and will advise further on how to prevent future infestations. They may also provide an ongoing preventative service to ensure that thrips populations do not reach damaging levels again.

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Frequently Asked Questions about Thrips

What do thrips look like?

Thrips are tiny, slender insects that can range in color from yellow to black. They have fringed wings and are usually less than 2 mm in length.

What do thrips eat?

Thrips feed on plant tissues, including leaves, flowers, and fruits. They use their sharp, needle-like mouthparts to pierce the surface of the plant and suck out the sap.

How do thrips damage plants?

Thrips can cause a variety of problems for plants, including discoloration, distorted growth, and reduced yields. They can also act as vectors for plant diseases.

How do thrips reproduce?

Thrips reproduce sexually, with females laying eggs on or in the plant tissue. The eggs hatch into tiny, wingless nymphs that resemble adults.

Are thrips dangerous to humans or pets?

Thrips are not dangerous to humans or pets, but they can cause an allergic reaction in some people.

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Conclusion

Hiring a professional qualified pest control company to get rid of thrips can provide peace of mind and save time and money in the long run. They can help to protect your plants and crops, prevent damage, and ensure that your farm or garden remains productive. A trained commercial pest control professional will have the technical knowledge and access to a range of professional use products and equipment which are not available to the public.

Looking for a Greener Solution?

Combat thrips with confidence—and conscience.

At PGM Pest Control, we champion Integrated Pest Management (IPM) strategies that blend science, sustainability, and peace of mind. Our eco-friendly pest control services target thrips without harming pollinators or delicate garden ecosystems.

What We Offer:

- Use of natural predators like Orius insidiosus and Amblyseius cucumeris.

- Low-toxicity treatments and selective biopesticides.

- Tailored monitoring pest plans.

- Ongoing support to manage pests throughout the growing season.

Whether you're a hobbyist or commercial grower, our green approach helps your plants thrive—while keeping ecosystems safe.

👉 Explore our Green IPM Services

Call PGM & Son on 01981 540088 or use our emergency number 07964 370 480. You can also email us, contact@pgmpestcontrol.co.uk or use the live chat facility on our website and if we’re not available on the live chat for any reason then there’s a handy message service for you to leave your details so we can call you back.

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PGM and Son

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