After hatching, lacewing larvae have very little on their minds other than hunting and feeding, which they do extremely well. They are voracious tiny eating-machines that have a particular fancy for aphids. In fact, they're so good at munching their way through these species that an entire industry has evolved, selling both the eggs and factory-bred larvae to gardeners and horticulturists as a natural and very effective method of controlling not only aphids, but also greenfly and other soft-bodied insects including young caterpillars.

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In the wild, the adult females will try to give their offspring the best possible start by laying their eggs in the vicinity of where aphids are present. They're typically laid on the underside of leaves or sometimes on stems where, in respect of the Chrysopid species, each egg is attached to a hair-like stalk that puts them out of reach, so that they're not eaten by the first hatching larvae. They go through three instar stages as they develop, typically over a period of two or three weeks, at the end of which they'll spin a cocoon to begin the short pupal stage of their life-cycle before becoming an adult.

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But it's the larval stage that we're interested in here and specifically the Chrysopidae green lacewing larvae that have two very different behavioural forms. The first, which is referred to as the 'naked' form, relies on stealth and then swiftness when hunting prey, whilst the second is deceptive and cunning. This second form disguises its presence by carrying a small packet of debris on its back that is constructed from various pieces of organic matter, such as bits of lichen or moss, shreds of dried leaves, fragments of snail shells and a multitude of other detritus, but also tiny parts of the carcasses of its victims.

 

The debris allows the larvae to hide in plain sight, which is not only useful in providing a safe retreat when its legs and mandibles are retracted and hidden from view, but also as a means of creeping up on its prey.

 

It proves particularly useful when they encounter aphids that are in the company of ants, as ants will attack predators such as ladybirds and lacewing larvae in order to protect what they see as a valuable food provider. It's a relationship that works well as the aphids secrete a sugar-rich sticky liquid called honeydew as they suck plant sap, that the ants need as a source of carbohydrates for energy. Whereas the 'naked' larvae would have to fight their way through, or find easier pickings, the debris-carrying larvae have discovered that if their debris packet includes some aphid parts or bi-products like wax or skin, they can often avoid detection. This cunning behaviour has been likened to the proverbial 'wolf in sheep's clothing'.

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Research has shown that the larvae are selective in terms of both the items they use and the way the packet is constructed and attached. Interestingly, the behaviour is only associated with green lacewings and only with certain species.

 

The Hemerobiidae brown lacewing larvae have a similar appearance to the 'naked' form of the green lacewing except that they are darker coloured, but the reproduction strategy is different as the females lay hundreds of eggs together on the underside of leaves rather than individually on their own protective stalk. If the eggs remain undetected, the larvae will hatch and then it will be a case of safety in numbers in the hope that you'll be one of those that will survive.