My last post began with the friarbird catching something that looked like an adult lacewing. This reminded me that I had some earlier photos of lacewings (Chrysopidae), such as this one of a typical adult green lacewing.
The lacewing story starts, of course, with their distinctive eggs. You may have seen them around your garden – a cluster of what looks like tiny white barrage balloons, all tethered by stalks to a base.
The eggs are really tiny, as can be seen by comparing these hatched eggs to the matchstick.
Laying each egg on a separate long stalk could be one way of saving the later-hatching eggs from cannibalism. However, it doesn’t always work—as can be seen from the following photos. When they hatch, the emerging larvae rest to let their cuticle harden. They are ferocious-looking, with huge mandibles. Inside the curve of the mandibles are the more slender maxillae, which are hollow and function like hypodermic syringes.
When feeding, the larva holds its prey with its mandibles, whilst using the maxillae to inject digestive juices capable of dissolving the internal organs of an aphid within 90 seconds (according to the Wikipedia entry). The resulting mush is then sucked back. In the photo below, the two hatchlings have almost completely drained their sibling’s egg.
After dispatching any brethren, the next step for a lacewing larva is to shin down the egg stalk, or drop directly to the ground. They then set about hunting their next meal, which can be anything small enough to tackle with those oversized mandibles. They have poor eyesight (their compound eyes have only about 5-6 ommatidia, just visible in the close-up photos as white dots) and seem to rely largely on their antennae to detect prey.
The most unusual thing about lacewing larvae, though, is what they do with their prey’s exoskeleton after the soft parts have been dissolved and sucked dry. They stick the remaining bits onto their backs, before setting off to look for their next meal. The practice is reminiscent of human head-hunters, with the heads of their victims strung on a strap or, less threateningly, of the Saucepan Man in Enid Blyton’s Faraway Tree. Here’s one example, hunting on a strawberry flower:
It’s thought that this bizarre practice provides camouflage, both visually and with scent, and perhaps some physical protection for what is quite a soft-bodied insect. This is the rear view of another larva:
Their voracious appetites (larvae have been recorded eating 100 aphids in one week) make the larvae good pest controllers, and lacewing eggs have been made available commercially for just that purpose. A recent ABC Landline program about the “Bananas with a red tip” described how their growers had eschewed artificial fertilisers and pesticides, allowing insects such as hoverflies and lacewings to flourish and successfully take over pest control.
Their growth completed, the lacewing larvae pupate in a cocoon before becoming adults. Lacewing imagoes are usually nocturnal, and less predatory than their larvae, preferring pollen and nectar.
The Chrysopid lacewings are part of the Neuroptera order which also includes antlions and mantidflies. Typically the adults have large compound eyes, powerful mandibles, and four wings which are patterned with veins. This one is from a different lacewing species:
If you want to know more about lacewing larvae, Paul Whitington’s site is an excellent one: https://southernforestlife.net/happenings/2018/1/23/hatching-of-a-lacewing-nymph
The ABC Landline program on red-tipped bananas is at https://www.abc.net.au/landline/red-tips:-the-story-behind-the-bananas-with-the/11126862