Lacewings are common flying insects about 12 - 15mm and with green bodies and lovely delicate green lacy wings which lie folded on their back when at rest. The adults eat only honey, pollen, and nectar, which they need to reproduce. The larvae, on the other hand, consume aphids, mealybugs, spider mites, leafhopper nymphs, caterpillar eggs, scales, thrips, and whiteflies.
They are best known as a predator of aphids, and fully deserve the nickname "aphid lion" as a single insect can consume 100-600 aphids in its lifetime. Adults hibernate over winter, and breed in the summer. The first larvae to emerge are brown , about 4mm long, with sharp nipping claws at the front (beware!). The older larvae are paler, about 13mm long, with bristles on their back. Lacewings are supplied as juveniles, or larvae.
We supply our lacewings in a large cardboard tube containing larvae in an inert carrier. They should be gently shaken out of the tube onto the plants and if the leaves are small, it may be helpful to wedge a small paper cone between the branches so that you can empty the contents of the tube into it, to avoid the Lacewing larvae ending up on the ground.
The Lacewing larvae should be introduced from May onwards, when the pests are present and when the temperature is consistently above 10°C although best control is gained at 15-20°C. Of course you can introduce them earlier if growing under cover, but don't introduce them if there are no aphids to feed on, or they will eat each other instead!
Further technical information here