Aphytis melinus is an internal parasite of the California Red Scale, Aonidiella aurantii

Aonidiella aurantii

Aonidiella aurantii or red scale is an armoured scale insect and a major pest of citrus. It is thought to be a native of South China but has been widely dispersed by the agency of man through the movement of infected plant material. In the USA it is known as California red scale...

, which is a pest of citrus

Citrus

Citrus is a common term and genus of flowering plants in the rue family, Rutaceae. Citrus is believed to have originated in the part of Southeast Asia bordered by Northeastern India, Myanmar and the Yunnan province of China...

 in California

California

California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...

 and elsewhere. This chalcid wasp

Chalcid wasp

Chalcid wasps belong to the insect order Hymenoptera, and are one of the largest groups within the order, with some 22,000 known species, and an estimated total diversity of anywhere from 60,000 to more than 500,000 species, meaning the vast majority have yet to be discovered and described.Most of...

 drums its antennae

Antenna (biology)

Antennae in biology have historically been paired appendages used for sensing in arthropods. More recently, the term has also been applied to cilium structures present in most cell types of eukaryotes....

 against the scale insect

Scale insect

The scale insects are small insects of the order Hemiptera, generally classified as the superfamily Coccoidea. There are about 8,000 species of scale insects.-Ecology:...

 to find out if it is healthy, if it is already parasitized, how large it is, etc., to decide how to use this prey. It has four choices (from worst to best): leave the scale to keep searching, feed directly on the scale, use the scale as a host for a male A. melinus, or use the scale for a female A. melinus.

If it accepts the scale as a host, the female will lay an egg in the host. When the egg hatches, the larva

Larva

A larva is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle...

l wasp consumes the internal organs of the pest. When finished with its host, the larva enters the pupa

Pupa

A pupa is the life stage of some insects undergoing transformation. The pupal stage is found only in holometabolous insects, those that undergo a complete metamorphosis, going through four life stages; embryo, larva, pupa and imago...

l, or cocoon, stage. From the pupa emerges the adult

Imago

In biology, the imago is the last stage of development of an insect, after the last ecdysis of an incomplete metamorphosis, or after emergence from the pupa where the metamorphosis is complete...

 wasp, smaller than the scale it consumed, which goes off in search of more scale insects.

This beneficial insect has controlled a key pest in citrus, significantly reducing pesticide

Pesticide

Pesticides are substances or mixture of substances intended for preventing, destroying, repelling or mitigating any pest.A pesticide may be a chemical unicycle, biological agent , antimicrobial, disinfectant or device used against any pest...

use on citrus in California.