Trichogramma Wasp

Trichogramma wasps are among the smallest insects in the world, with adults measuring only a fraction of a millimeter. They belong to a genus of minute parasitoid wasps that develop entirely inside the eggs of other insects, chiefly moths and butterflies.

These wasps have a nearly global distribution and are found wherever their host insects live, from farm fields to gardens and wild habitats. Because they attack the eggs of many caterpillar species before those pests can hatch and feed, trichogramma wasps are widely used as biological control agents in agriculture.

Despite their tiny size, these wasps are efficient hunters, with females detecting host eggs by scent and touch. A single moth egg can host the complete development of one or more trichogramma wasps.

Look for these features:

• Extremely tiny size, roughly 0.3 to 0.5 mm, near the limit of unaided vision
• Stout body, usually yellowish to brownish
• Short, few-segmented antennae
• Fringed wings visible only under magnification
• Almost always associated with the eggs of moths or butterflies

Due to their size they are hard to distinguish from other minute wasps without a microscope, but their association with host eggs is characteristic.

Trichogramma wasps occur worldwide in nearly every terrestrial habitat where their host insects are present, including croplands, orchards, gardens, grasslands, and forests. They are active in warm growing seasons and are commonly reared and released in agricultural settings for pest management.

Female trichogramma wasps search foliage for the eggs of moths and butterflies, then lay their own eggs inside them. The developing wasp larva consumes the host egg contents, preventing the pest caterpillar from hatching. This egg-parasitoid behavior makes them valuable natural enemies of many crop pests and important regulators of insect populations.

Trichogramma wasps undergo complete metamorphosis entirely within a single host egg. A female inserts one or more eggs into a host egg; the larva hatches inside, feeds on the contents, and pupates there, often turning the host egg dark. The adult then chews its way out. The full cycle is very rapid, sometimes only a week or two in warm conditions, allowing many overlapping generations per season.