Metaphycus helvolus facts for kids

Metaphycus helvolus is a tiny parasitic wasp that comes from South Africa. It belongs to the Encyrtidae family. This special wasp is a parasitoid of soft scale insects. People have used it to naturally control these pests. This method is called biological control. It has been very helpful in places like California and Australia.

What it Looks Like

Metaphycus helvolus is a very small insect. The adult female wasp is yellowish-orange. She is only about 1 millimeter (or about 1/64 of an inch) long. That's smaller than a grain of rice!

Life Cycle and Habits

The adult female Metaphycus helvolus wasp searches for certain host insects. Her most important host is the Mediterranean black scale. She also targets other scale insects. These include brown soft scale and nigra scale.

When she finds a young scale insect, she uses her ovipositor (a special egg-laying tube). She pokes a hole in the scale insect's skin. Then, she lays an egg inside. This process can take several minutes. It works best when there are no ants around. Ants sometimes protect scale insects.

The wasp larva (baby wasp) grows inside the scale insect. It eats the scale insect from the inside. This kills the scale insect. When the wasp larva is ready, it chews a round hole. Then, it comes out of the dead scale insect.

These wasps can have many generations each year. This means they reproduce faster than the black scale. Adult wasps also feed on scale insect nymphs. They poke a hole and drink the liquid that comes out.

Helping Farmers with Biological Control

The black scale is a serious pest for citrus trees. It causes a lot of damage in many parts of the world. In 1926, this pest was causing millions of dollars in damage in California.

In 1937, Metaphycus helvolus was brought to California. It quickly helped to control the black scale. Within four years, the number of black scale pests dropped a lot. Less than 1% of citrus farms had serious problems.

After this success, the wasp was sent to South Australia in 1942. There, it also helped reduce the scale insects on citrus trees. Thanks to this tiny wasp, the scale insect became a minor pest in Australia.