Found on cow parsley

Thrips (order Thysanoptera) are very small creatures that are almost invisible to the naked eye. Without magnifying glass they look like small black stripes on the leaf. Thrips is a very feared plague among growers. They are very difficult to control, even though the damage to the plant is not too bad. They are so feared because these insects have wings, so they can spread rapidly to other plants.

 

In a living room this is a little less dangerous than in a greenhouse with thousands of plants, but it is important that a thrips infection is combated as quickly as possible. Thrips poke in the leaves in search of nutrients. These punctures leave gray spots on the leaf. Since gray spots do not often occur on a plant, this is a good way to recognize thrips. Thrips can also infect a plant with a virus. This is the most dangerous thing about thrips, since a virus can cause plants to die.

 

Thrips are very difficult to combat, over the years thrips have become immune to many pesticides. And because they can fly, it is very difficult to get hold of the entire colony. Often, chemical pesticides are used for the infection of thrips. A remedy you can still try at home is a solution of soft soap (20 g per liter of water) and 10 ml of spirit or methanol. With this you spray the plant several times a week until the pest is gone.

Thrips like warmer temperatures and low humidity. During winter when it is cold, they will sit around 8 cm below ground. In spring they then reappear to reproduce. Preventing thrips is quite difficult, especially since this insect can fly. Therefore, pay close attention if you see gray spots on your plant, the sooner you can fight an infection the better. 

The microscope slide was prepared using enzymes as a clearing agent and Hoyer’s fluid as a mounting medium. Hoyer’s mounting medium clears soft tissue in the preparation and improves visibility of the object because of its high refraction index.

With thanks to Hans Huijbregts NGVM, Dutch Society For Microscopy