Thrips reproduce through egg-laying. Learn to recognize these tiny egg nests to prevent the pests from spreading across your plants!
Key thrips egg facts
Size – 1/64th inch (0.2 mm)
Per cluster – 2 to 200
Color – white or yellow
Location – inside leaves, stems, underside of leaves
Hatches in – 2-7 days
Thrips aren’t always dangerous, but knowing what you’re dealing with helps prepare for the worst. Locating thrips eggs is a great first step!
Where do thrips lay eggs?
Thrips eggs are lain on or in soft tissue. Most of the pest species actually lay their eggs inside the plant, in a small wound. These are usually thrips of the Terebrantia sub-order.
This is usually in:
- leaf stems
- young leaves
- flower buds
- leaf buds
- soft wood stems
Sometimes this infection triggers galls on the host plant.
- Plant material starts growing in a bloated, blistering manner.
Some thrips lay their eggs without wounding the plant.
- They find tight crevasses in bark and leaf joints and wedge their eggs inside.
- Some of them attach their eggs to the underside of leaves with a special glue.
- About half of the different species of thrips are like this: the Tubulifera sub-order.
This special glue that is used is actually a combination of proteins and compounds the thrips produces. It’s very successful in preventing eggs from falling off due to wind and other disturbances!
How do thrips lay eggs?
For most thrips, a special pointed organ called an ovipositor is located at the end of the female thrips’ abdomen. This is used to slice through outer plant tissues.
- Shown right is a close-up view of this organ with a microscope.
- At the tip of the needle, the saw-like organ appears.
- Muscles activate it and pull it in and out, piercing plant skin and creating a hole.
The thrips then inserts a single egg in this wound.
- Most species lay two or three eggs a day.
- It’s possible to locate these “egg nests” with careful observation. A magnifying glass helps.
- White dots appear along stems or leaf veins. Each dot has one, sometimes several tiny eggs inside.
The eggs are quite large compared to the adult. Each egg is often about one-fifth of the length of the adult thrips body.
Thrips of the Tubulifera order don’t have this ovipositor. Instead, they’ve developed powerful glues that seal their eggs in place.
- Hatching is easier and nymphs can directly start feeding.
- However, eggs are more vulnerable to thrips-eating predators.
Parthenogenesis, no need for male thrips!
Normally, for most insects, unfertilized eggs result in male hatchlings, whereas a fertilized egg produces a female specimen.
However, many thrips species are able to reproduce even when no males are present. This is called complete parthenogenesis. In this case, an unfertilized egg produces a female specimen. Usually this is the result of an infection by a particular bacteria that interferes with the reproductive system.
- In this particular type of parthenogenesis, called thelytoky, females lay unfertilized eggs that are females. These are near clones of the mother and always develop into reproducing females as well.
- Some thrips species known to have both male and female genders are present in North America only in their female form!
Thrips eggs hatching
Within two to seven days, the eggs hatch under the surface. For thrips, the hatchling is quite similar to the final adult, but smaller in size and often lacking wings. It chews its way to the surface and starts crawling around to find a place to feed.
- When insect hatchlings bear a close resemblance to adult insects, they’re called nymphs.
- When they’re very different, as the caterpillar is to the butterfly, they’re called larva.
For thrips, the word “nymph” is more correct than the word “larva”.
As soon as they hatch, the thrips nymph is already equipped with mouthpieces to feed.
It even has a rather successful way of defending itself against predators! It curves its abdomen back upwards, and then releases the strain in a powerful flick! This helps it fight off many pest-eating insects like other beneficial thrips, ladybugs, and more!
- Read on to discover the next steps in the thrips lifecycle.
Credits for images shared to Nature & Garden (all edits by Gaspard Lorthiois):
Thrips colony on leaf by Alan Manson under © CC BY 4.0
Stephanotis with thrips eggs by Jane Dickson, Nature & Garden contributor
Ovipositor with microscope by Alex Bairstow under © CC BY-NC 4.0
Close-up of thrips eggs by Nasser Halaweh under © CC BY-NC 4.0