Overview & Lesson Sequence

Focus on Standards & Assessment

Materials Needed, Preparation & Planning, Management Strategies

Background Info

Intro Activity
Why Study Predator - Prey interactions?

Activity 1
Observation of a predator-prey interaction

Activity 2
What makes a predator successful?

Research Project
Designing a predator - prey experiment

Optional Activity
Biological Control vs. Pesticides

Case Study
Rabbits in Australia

References

Glossary

Suppliers

Resource Sheets
-Plant Propogation
-Rearing Aphids
-Eyelash Brush
-Petri Dish Habitat
-Sampling Methods
-Observation Check Sheet
-Sample Rubric for Group Presentation
-One Gallon Cage
-Predators in the Environment Data Sheet
-Predation Inquiry
-Green lacewing Larval Mouthparts
-Chewing Mouthparts
-Hemipteran Mouthparts

Rearing
-Green lacewing
-Ladybird Beetle
-Big eyed Bug
-Praying Mantid
-Aphids
-Fruit Fly

Anatomy
-Green lacewing
-Ladybird Beetle
-Praying Mantid
-Big eyed Bug

Enforcers Home

CISEO Home

Green lacewing Rearing

Natural History
Green lacewings are in the insect order Neuroptera and are found in most environments throughout North America. There are several species and the most common, Chrysoperla carnea, occurs throughout North America, while other species are more restricted in distribution. Adults feed on pollen, nectar, and aphid honeydew, but the larvae are voracious predators.  The pale green adults are 12-20 mm long, have long, slender antennae, prominent eyes, and large, veined, transparent wings. They are slow-flyers and are most active during the evening and nighttime hours.  Female lacewings can lay up to 300 eggs over a period of 3-4 weeks, if they survive that long.  Eggs are usually laid singly or in groups on leaves near aphid colonies.  Each egg is held away from the leaf surface by a slender, silken stalk. The larvae, commonly called aphid lions, resemble small pinkish-brown and cream alligators with prominent pincer-like jaws.  When a larva encounters an aphid or other prey, it seizes and punctures it with its jaws, injects a paralyzing venom along with some digestive juices, scrambles the innards with the tips of its mandibles, and sucks out the body fluids. Several studies estimate that larvae can consume approximately 100-600 aphids during this stage of their development.  Lacewings have complete metamorphosis and after feeding and growing through 3 instars to about 8 mm in length during a 2-3 week period, the larva spins a spherical, white, silken cocoon in which it pupates. The adult emerges in about 5 days through a round hole that it cuts in the top of the cocoon. Some species of Chysoperla overwinter as pupae and others as adults.

Aphid lions are generalist predators and will consume aphids, mites and a wide variety of other soft-bodied insects, including insect eggs, thrips, mealybugs, immature whiteflies, and small caterpillars. They will also consume each other if no other prey are available. They are quite active and will travel 80-100 feet in search of prey.  Once their food source is exhausted they will leave the area.  These insects are extremely effective predators under certain conditions, especially in protected or enclosed areas such as a greenhouse, but they may fail to survive and provide control when conditions are too dry or too moist.

Rearing
Green lacewing eggs and larvae are available from many commercial suppliers (see Suppliers) or can be collected from the wild.  Most experiments require large larvae so it is recommended that you collect or order larvae.  If you decide to collect the aphid lions in the wild, search on plants that are heavily infested with aphids or whiteflies.  Larvae should be reared singly in individual wells (such as those used for Elisa plates), or in a group in a large Tupperware-like container with Vaseline or Fluon (see Suppliers) painted on the inside upper edge to prevent escape.  In the latter situation, crumpled paper towel is needed to create increased surface area and hiding places as the larvae will eat each other.  Purchased larvae often come in a cut piece of corrugated cardboard with silkscreen glued to either side.  A single larva resides in each of the small cells or corrugations provided by the cardboard.  It is important not to remove the silkscreen until you are ready to perform the experiments since larvae will quickly disperse from their cells and begin eating each other.  Purchased aphid lions can be fed artificial diet (see Cohen 1998 in References) while wild-caught larvae can be fed aphids, purchased insect eggs, or artificial diet.  To avoid the hassle of providing food for the hungry larvae, try to order or collect the larvae such that they arrive one to two days before the experiment.  Keep the larvae in a humid environment until you are ready to use them.

For the truly dedicated educator, adult lacewings can be collected and housed in a large jar or small aquarium with adequate ventilation and a Petri dish filled with moist cotton or peat moss to provide moisture.  A 1:1:1 slurry of sugar, water, and brewers yeast smeared on a popsicle stick and leaned against the side of the cage provides a food source for the adults. The addition of a few cut stems from an infested plant placed in a florist's water pick may encourage the adults to lay eggs.  Eggs hatch in approximately 7-10 days and can be fed as described above.

Lacewing adults, larvae and eggs are quite fragile and are best handled with a fine brush.