ANTLIONS, LACEWINGS, AND RELATIVES: Neuroptera

PHYSICAL CHARACTERISTICS

Adult neuropterans (new-ROP-te-ruhns) are long, slender, soft-bodied insects measuring up to 0.12 to 3.15 inches (3 to 80 millimeters) in length with wingspans up to 5.63 inches (143 millimeters). The head is distinct with well-developed compound eyes, or eyes with multiple lenses. In owlflies, each compound eye is divided into an upper and lower section. Simple eyes, or eyes with only one lens, are found only in the moth lacewings. The chewing mouthparts are directed downward or forward. The antennae (an-TEH-nee), or sense organs, are long and thick, threadlike, feathery, or swollen at the tips. The thorax, or midsection, is divided into three segments. The first segment is shorter than the last two wing-bearing segments. In most species the four clear wings are long, narrow, and held like a roof over the body when at rest. The wings are reduced in size or absent in a few species. In most species the wings all have a lacey network of finely branched veins. The forewings may or may not be similar in size or shape to the hind wings. For example, the hind wings of spoonwing lacewings are very slender and shaped like long-handled spoons, while the forewings are shorter and normal in shape. The legs are long and slender. The legs of antlions and owlflies are spiny with well-developed claws for capturing insect prey on the wing. Mantidflies use the front legs for grasping insect prey. The abdomen is long and slender.

The larvae (LAR-vee), or young of an animal, do not resemble the adults at all and are wingless. Their bodies are usually flat and tapered at both ends; only rarely are they thick and grublike. Their heads are flat with mouthparts directed forward. The jaws are long and may be toothed or smooth. Some spongilla fly larvae have jaws that are longer than their bodies. The jaws are used for stabbing prey and sucking out their body fluids and tissues. Like most insects with chewing mouthparts, neuropterans have two sets of jaws that lock together to form a hollow tube that works as both a syringe and a soda straw. The larvae pump digestive chemicals through the tube into their victims and suck out their liquefied internal organs. They are equipped with only five to seven eyespots on each side of the head, and their eyesight is very poor. The antennae are long or short.

The thorax is usually short and wide, but on the larvae of spoonwing lacewings the first segment of the thorax is long and necklike. The legs are long in climbing species such as green lacewings. In antlions and owlflies, the legs are short and strong for digging. The legs are greatly reduced in mantidflies that feed on spider egg sacs. The abdomen is long or egg-shaped. Both thorax and abdomen may be covered with fleshy projections and bristly hairlike structures.

GEOGRAPHIC RANGE

Neuropterans live on all continents except Antarctica. There are about six thousand species of neuropterans worldwide, with four hundred found in the United States and Canada.

HABITAT

Adults are often found on vegetation. The larvae are usually more specific in their selection of habitats, preferring certain soil types, freshwater habitats, or other locations that guarantee the availability of certain kinds of prey. The larvae of antlions and spoonwing lacewings prefer sandy habitats mostly in drier regions. Those of green and brown lacewings are found only on shrubs and trees. Larval dustywings also prefer trees and shrubs and are usually quite specific about the species of plant. Others prefer freshwater streams or hunt under rocks or in leaf litter along the shore. The larvae of moth lacewings are grublike and live among the roots of plants.

DIET

Most adult and larval neuropterans are predators (PREH-duhters) that will hunt for and eat anything they can catch, especially insects. However, the larvae of some species specialize and eat only certain kinds of animals, such as freshwater sponges or spider eggs. For example, the larvae of most mantidflies eat only spider eggs. A few species are not predators at all and eat sap from the roots of trees and shrubs. Many adults are omnivores and will eat both plant and animal tissues, including soft-bodied insects, honeydew, and pollen. However, spoonwing lacewings and green lacewings eat only pollen and nectar from flowers. Antlions, owlflies, and mantidflies are strictly predators, although antlions will occasionally scavenge freshly dead insects.

BEHAVIOR AND REPRODUCTION

Many adult neuropterans are active at dusk or in the evening and are attracted to lights. During the day they remain inactive and hidden among vegetation. Some species rely on camouflage to avoid detection by predators. Some brown and green lacewings will pretend to be dead when threatened. Others produce a bad odor to discourage predators. Some mantidflies not only mimic the color and appearance of paper wasps but will also adopt their movements and postures when disturbed.

Larvae engage in a variety of behaviors to capture prey. The larvae of owlflies are "sit-and-wait" predators, ambushing hapless prey as they walk into their open jaws. Some antlions hide at the bottom of cone-shaped pits they construct to trap crawling insects. Green lacewings, brown lacewings, and dustywings actively hunt for prey, as do larvae living in freshwater habitats. Spongilla flies eat only freshwater sponges and moss animals and use their incredibly long and slender jaws to pierce individual cells. Some species living along the shore use their long jaws to probe wet sand and mud for fly larvae. Pleasing and silky lacewings hunt in crevices and under bark for arthropods (AR-thruh-pads), or animals with hard outer skeletons and several pairs of jointed limbs, such as insects and spiders. The first and third stages of beaded lacewing larvae burrow in the soil in search of termites, while the second state is inactive and does not feed.

The larvae of mantidflies feed in spider egg sacs or in the nests of social wasps. Immediately after hatching, the larvae that prey on spider eggs actively seek a suitable host spider and climb up on its body. Eventually the larvae enter the egg sac to feed. The second and third larval stages look very different from the first stage and have very large, bloated abdomens. Scientists think that these larvae might produce chemicals that slow down the development of the spider eggs to give them plenty of time to feed. Mantidfly larvae are specialists and attack only a single species or several closely related species of spiders.

Only two groups of neuropteran larvae are not predators. Moth lacewings eat sap from the roots of trees and shrubs as they burrow through the soil. It is not known what the larvae of giant lacewings eat, but their mouthparts are blunt and unsuitable for stabbing insect prey.

Many neuropterans use chemicals to communicate with potential mates during courtship. Males have special organs on their abdomen or wings that produce pheromones, chemicals that are attractive to females. Green lacewing males use sound to attract mates, vibrating their abdomens to communicate with females.

Males and females must mate to produce eggs that will develop into larvae. Males deposit sperm directly into the reproductive organs of the female. Mating is either brief or lasts up to several hours. Mating usually occurs when a male and female meet, but swarms of mating moth lacewings have been observed in Australia and the United States.

WAY TO GO!

The insect digestive system has three sections: the foregut, midgut, and hindgut. Larvae of this order are unique in that the midgut is not connected to the hindgut. As they feed, their waste is stored in the midgut. They cannot rid their body of waste until they reach adulthood and gain a fully formed digestive system. A lifetime of waste is released as a single pellet as they emerge from the pupa.

The life cycle of neuropterans includes four very distinct stages: egg, larva, pupa, and adult. Eggs are laid one at a time or in batches on rocks, bark, or in crevices of bark. Some species of green lacewings, mantidflies, and split-footed lacewings lay a single egg on top of a silk stalk. This keeps them out of the reach of hungry predators, especially other lacewing larvae. There is little or no parental care of the eggs. The larvae look nothing like the adults and do not live in the same habitat. The larvae usually molt, or shed their exoskeletons or hard outer coverings, three times over several months or years before transforming into a pupa. The pupa is formed inside a silk cocoon. Neuropteran larvae produce silk with special organs inside their abdomen. These same organs work like kidneys in other insects, filtering out waste in the blood. The legs and wings of the pupa are not completely attached to the body and the abdomen is capable of some movement.

NEUROPTERANS AND PEOPLE

The larvae of both green and brown lacewings are known as aphidlions, and they prey on pests in a variety of garden, greenhouse, and agricultural situations. They are sold to gardeners and farmers as eggs. The adults are also reared by the thousands and released among various crops to control insect and mite pests.

CONSERVATION STATUS

No species of neuroptera are endangered or threatened. Since many species are known to be from very small geographical areas, they are especially vulnerable to habitat destruction due to human activities. Several countries, states, and provinces list species of neuroptera that are considered rare or possibly threatened with extinction.

GREEN LACEWING (Mallada albofascialis): SPECIES ACCOUNTS

Physical characteristics: This species is one of the small lacewings. The light to dark green body is long and slender, with broad wings. The head and first segment of the thorax have red patches. The face has a distinctive white area above the mouth. The larvae are long and have special hairs on their backs. The hairs are used for holding debris that helps to camouflage the larvae.

Geographic range: Green lacewings are found in the Northern Territory and in coastal Queensland, Australia.

Habitat: They live in forested areas.

Diet: Adults eat honeydew and flower nectar. The larvae eat soft-bodied arthropods, especially mealybugs.

Behavior and reproduction: Little is known about the behavior of this species. The larvae climb trees and shrubs to hunt for food. Adult females lay single eggs on the tips of silk stalks. The eggs are laid in batches of ten to fifteen.

Green lacewings and people: This species does not impact people or their activities.

Conservation status: This species is not listed as endangered or threatened. ∎

MOTH LACEWING (Megalithone tillyardi): SPECIES ACCOUNTS

Physical characteristics: The moth lacewing is a relatively large, robust insect that resembles a moth. The body and wings are dull brown. The body is covered with numerous long hairs. The wings are folded like a roof over the body. The larva are grublike.

Geographic range: Moth lacewings are found in Southeastern Queensland and in northern New South Wales, Australia.

Habitat: This species is found at higher elevations, often on sandy soils. Larvae burrow through soil.

Diet: It is not known what the adults eat, if they eat at all. The larvae feed on plant sap through the roots of trees.

Behavior and reproduction: Adults emerge in large numbers and gather in large mating swarms made up of many more males than females. This swarming behavior may last as long as three weeks.

The females emerge from the pupa with their reproductive organs blocked with a plug. The plug is apparently removed by the act of mating.

Moth lacewings and people: Swarms of these insects sound like a hailstorm when they hit the metal roofs of houses. Their swarms can be a nuisance when they enter homes, which happens rarely.

Conservation status: Moth lacewings are not listed as endangered or threatened. As with most organisms, habitat destruction seems to be the greatest threat. However, the vulnerability of this species is difficult to determine because the larvae are hidden in the ground, and swarms of adults do not appear very often. ∎

MANTID LACEWING (Euclimacia torquata): SPECIES ACCOUNTS

Physical characteristics: The mantid lacewing is a medium-size lacewing. The body is robust with narrow wings that are darkened along their leading edges. This species is wasplike in appearance and is brightly marked with black, yellow, and orange. The front legs are used for grasping insect prey. The larvae are unknown.

Geographic range: The species is found in Queensland, Australia, and in Papua, New Guinea.

Habitat: This species lives in forested areas.

Diet: Adults eat any insects they can catch. The larvae probably eat spider eggs of a particular spider or group of closely related spider species.

Behavior and reproduction: Adults protect themselves by looking and behaving like paper wasps. Nothing is known about their reproductive behavior.

Mantid lacewings and people: This species does not impact people or their activities.

Conservation status: This species is not listed as endangered or threatened. ∎

ANTLION (Myrmeleon formicarius): SPECIES ACCOUNTS

Physical characteristics: Antlions are very long and slender insects. The head and thorax are short and thick, while the abdomen is very long and slender. The body is brown with tan markings. The antennae are thickened, especially at the tips. The wings are long, narrow, and transparent with brown, black, and white spots. The larvae are robust and egg-shaped with large curved jaws. Their body is built or adapted for burrowing backward through sandy soil.

Geographic range: Antlions are found in Western Europe.

Habitat: Antlions live in a wide variety of habitats, especially grasslands and sandy deserts.

Diet: Adults capture all kinds of flying insects on the wing. The larvae seize any small insects that fall into their pits.

Behavior and reproduction: Adults are active at night and rest on foliage during the day. The long body and brown color helps them to blend in as they lie perfectly still and flat on a twig or branch. The larvae dig cone-shaped pits in loose, sandy soil. They rapidly flick sand out of the pit with their flat heads. They hide at the bottom of the pit with only their jaws exposed. When a suitable prey falls into the pit, the larva will quickly impale it with its jaws and inject it with paralyzing venom. It will then pull the prey down into the sand. They will abandon their pits and quickly burrow deep in the sand when threatened by anything larger than a small prey animal.

Adult females lay their eggs in sandy soil. The larvae burrow through the soil until they find a suitable place to dig a pit. They prefer sandy areas under rocky overhangs or in caves. By choosing these protected sites, the larvae avoid rain that will ruin their pits or cause them to drown. When fully grown, the larva spins a spherical cocoon made of silk coated with particles of sand.

Antlions and people: Antlion larvae, or "doodlebugs," have fascinated humans for centuries. They are featured in folktales, especially in the chants and charms of European children. The charms specifically refer to their cone-shaped pits and backward movements.

Conservation status: This species is not listed as endangered or threatened. ∎

SPOONWING LACEWING (Nemoptera sinuata): SPECIES ACCOUNTS

Physical characteristics: Spoonwing lacewings are large to medium-size insects measuring approximately .63 inches (16 millimeters) in length, with a wingspan up to 2.16 inches (55 millimeters). The body is long and thick, with relatively broad, rounded forewings. The hind wings are particularly long and slender and are narrower at the base than they are at the tips. The wings are marked with irregular yellow and black bands. At rest the forewings are held over the body, while the hind wings project toward the rear. The larvae are broad and egg-shaped, with short necks and short jaws.

Geographic range: Spoonwing lacewings live throughout Europe and in parts of North Africa along the Mediterranean Sea.

Habitat: They live in forests and open grasslands.

Diet: Adults feed at flowers on pollen and nectar. The larvae bury themselves in sand and remain inactive for long periods. They actively hunt for prey on the surface of the soil. When an insect approaches, the larvae detect their movement through vibrations in the soil. The larvae approach potential prey slowly and attack, stabbing it with their sharp jaws. They will occasionally eat other spoonwing lacewings.

Behavior and reproduction: Adults are active during the day in late spring. Females lay their eggs in sand. Probably one generation is produced every year.

Spoonwing lacewings and people: This species is not known to impact humans or their activities.

Conservation status: This species is not listed as endangered or threatened. ∎

FOR MORE INFORMATION

Books:

"Neuroptera (Lacewings)." In The Insects of Australia, edited by CSRIO. 2nd edition. Vol. 1. Carlton, Australia: Melbourne University Press, 1991.

Tavolacci, J., ed. Insects and Spiders of the World. Volume 1: Africanized Bee-Bee Fly. Volume 5: Harvester Ant-Leaf-cutting Ant. Volume 8: Scorpionfly-Stinkbug. New York: Marshall Cavendish, 2003.

Web sites:

The Antlion. http://kaweahoaks.com/html/antlion.htm (accessed on October 13, 2004).

"Green lacewings. Chrysopidae." BioKids. http://www.biokids.umich.edu/critters/information/Chrysopidae.html (accessed on October 13, 2004).

"Neuroptera. Lacewings, antlions." Ecowatch.http://www.ento.csiro.au/Ecowatch/Insects_Invertebrates/neuroptera.htm (accessed on October 13, 2004).

Neuroweb. http://neuroptera.com/main.html (accessed on October 13, 2004).