Biological Predator: Green Lacewings

by Alex Robles

Biological predators are my first line of defense and best answer for pest management in my gardens.  I don’t have to worry about pest developing a resistance to them like I would with certain pesticides.  But I do know that a certain number of pests have to be in the garden for predators to want to stay and feed, Green Lacewings are no different.  There are about 1,200 green lacewing species are known worldwide.  They are great general predators that will attacks insects and insect eggs, such as aphids, small caterpillars, mites, whitefly, scale, mealybug, thrips, psyllids, and other soft-bodied insects.

Green Lacewing Adult – Texas A&M

What are they.  

  • Adults Green Lacewings will have light green bodies with long skinny antennae and golden eyes.  Their wings are long, lacy, veined and clear, about 1/2 to 3/4-inch long.
  • Lacewing adults live for about 30 days and are vegetarian, which means they eat pollen, nectar and insect honeydew, not pests.  That’s why some farmers tolerate very light infestations of pests that make honeydew (aphids, whiteflies). The longer the adults stick around, the more likely they are to lay eggs.   Adults are poor fliers and are most active at night.
  • CHRYSOPERLA RUFILABRIS is the species of lacewing that I’ve use with great results.  They’ll have a bit of red on both sides of head and black cross veins.  They’re best known in the Southern and Eastern U.S. for controlling aphids in tree (pecan) and field crops;
  • Green lacewings larvae are great general predators that will feed on the eggs and young larvae pests like the Colorado potato beetles, flea beetles, most worm pests (caterpillar, budworms, borers, cabbage loopers, codling moths), aphids, spider mites, scales, psyllids, mealybugs, whiteflies, thrips, leafhoppers and other pests.
  • Mated females will lay about 10-30 egg a day.  The white eggs are laid on the leaves on top of silk stalks or hairs which keep young larvae from eating each other after they hatch.  They look like balloons on a string.
  • When the larvae hatch they have a grayish-brown color and will be about 3/8 inch long when full-grown.  To me they kind of look like ladybug larvae, just a different color.
  • The larvae are predators for about 2-3 weeks.  They use their pincer-like jaws to grab the prey, inject digestive enzymes into it and suck out the liquified inereds.
  • The larvae are called “aphid lions” because they’re extremely carnivorous and prey on a lot of soft-bodied insects
  • During 2-3 weeks of larvae life, one lone lacewing larva can eat 250 leafhopper nymphs in grapes, 300-400 aphids, 11,200 spider mites, 3,780 coccid scale crawlers or 6,500 scale eggs on pine trees.
  • Larvae grow through three stages (instars) for 2 to 3 weeks before they spin a white silken cocoon around themselves.  After about 5 day the adults emerge from their cocoons and will migrate towards pollen, honeydew or feeding station.

Environment

  • At 80º F (27º C), larvae hatch from their eggs in 3 to 5 days from date of shipment.  For each 5 degrees of higher temperature, larvae will clean up aphid infestations a week sooner (higher metabolism makes them eat more).
  • Temperature of at least 60º F (15.5º C) is required for significant eating and egg-laying.   They move from plant to plant if leaves are touching – slower on rough or hairy foliage.
  • Green lacewing larvae are very effective in dense foliage where pests are evenly distributed, and on low growing plants.  It’s said that the larvae can walk up to 7 miles
  • Corn and sunflowers are some of the plants in my garden that help me make a welcoming environment for adult Lacewings.

There are specific seed flower/plant mixes that are sold to attract beneficial predators not just Lacewings.

Green Lacewing eggs – University of Kentucky

How to release them.

Lacewings are available from insectaries in a all three stages of life.  Below is list of what’s out there. I’ve only used the eggs that are glued to cards that i’ll cut into smaller squares, then I’ll hang them around the garden.

  • Loose eggs in increments of 5,000 and 10,000 in bags or cups with or without rice hulls or vermiculite and food.
  • Eggs glued on cards (2,500, 5,000, or 10,000/card) perforated to cut into 30 hangable units.
  • Pre-hatched larvae in cardboard honeycomb units (500 larvae/unit) come as first instar (young and small) or third instar (larger, faster and hungrier, that pupate sooner).
  • Pre-hatched larvae 1,000/bottle in rice hulls (2 week notice required).
  • Adults in cartons of 100 or 250 mated females.

What to look out for:

Remember “Ants” are attracted to the eggs on the card, I learned this the hard way. They will eat all the eggs on the card. Ants generally interfere with biological predators, and in particular they attack and drive lacewing larvae away from aphids, whitefly, mealybug, and soft scale. These honeydew-secreting pests supply sweets to the ants. Your going to need to control any ant population in your garden.  Other things that could interfere with the Green Lacewing larvae from attacking a pest are hard shells or waxy coating on them. Also low temperatures will also slow down their feeding or metabolism.

Don’t forget, that whatever biological predator that you use, you’re going to need to find a way a  to keep egg laying adults interested in staying in your garden. Either by allowing a certain number of pests or by planting those plants they find attractive.  Chemicals are the last line of defense for me because I know that pesticides will the pests as well as any beneficial biological predators. Which would leave my garden defenseless until the beneficial population could be built up again.

Let the circle of life help manage your garden pests with you.  Go get some biological predators.

Grow Learn Teach

Resources:

Entomology at the University of Kentucky:  https://entomology.ca.uky.edu/ef148

Texas A&M:  https://texasinsects.tamu.edu/green-lacewing/

Rincon-Vitova Insectary:  http://rinconvitova.com/lacewing.htm

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