The biology of Chrysopidae and Hemerobiidae (Neuroptera), with reference to their usage as biocontrol agents: a review

• 1 Many regions have well-developed faunas of Chrysopidae and Hemerobiidae, many of which are potential control agents, but only a few widely distributed species have been seriously considered as such.
• 2 Most of the biological information available concerns Chrysopa species in north temperate areas. C.carnea Stephens, in particular, has been utilised in many pest control programmes. Prepupal or adult diapause constitutes a well-defined stage in the life cycles of many temperate species.
• 3 Larval searching behaviour is efficient, and larvae of most species studied can utilise a wide range of prey organisms or sugar-based foods. The quality of the larval food can affect reproduction of the ensuing adults. Cannibalism is frequent, and may serve as the main food supply when other sources are scarce. Artificial diets for mass rearing are outlined.
• 4 Adult Hemerobiidae are predators. Adult Chrysopidae are either predators or honey-dew feeders, the latter possessing symbiotic yeasts which aid amino acid synthesis. Sprays based on sugar and yeast hydrolysates can be applied in the field as (i) attractants and (ii) alternative or additional food.
• 5 A wide range of predators and hymenopterous parasites attack all stages. Many widespread and non-specific parasites may attack lacewings introduced from other areas.
• 6 Potential use of Chrysopidae and Hemerobiidae in integrated control is enhanced by their tolerance to some insecticides.
• 7 Lacewings are potential control agents of pests in greenhouse, field crops, and orchards. Native species should be augmented rather than others introduced. It would probably be wise to encourage only one or few lacewing species against any given pest.