Physical Characteristics: Asparagus aphids are tiny, soft-bodied, blue/green to gray green insects about the size of a pinhead. They are covered with a waxy film.
Behavior: Aphids feed on the sap of a plant. They generally attack in colonies gathering on the underside of leaves. Aphids produce a waste product called honeydew, which can cause sooty mold on plants. They have the potential to carry viruses through their sucking mouthparts.
Damage: Aphids inject a toxin into the plant while feeding which will result in distorted ferns. Because asparagus is a perennial, this distorted growth will not be able to adequately feed the crown and roots and may result in plant death within a few years.
Management: Removing dead foliage and tilling in the spring is the main control method for this insect. They also have many natural enemies including lady beetles, flower fly larvae, lacewings, parasitic fungi, and parasitic wasps.
If more aggressive measures are necessary, aphids can be controlled with insecticidal soaps or other insecticides labeled for this purpose.
Physical Characteristics: The adult beetle is dark orange with black spots, ¼” in length. The grub is dark green/gray.
Behavior: The grub as well as the adult will feed on asparagus ferns, stems, and spears.
Damage: They are of particular concern on tender, young plants that may not be strong enough to survive the damage.
Management: To discourage feeding of the spears, allow ample fern growth at the edge of the garden to attract the beetles away from the spears. If more aggressive measures become necessary use a pesticide labeled for the purpose.
Grubs will overwinter in mulch so be sure to keep it a few inches from the base of the asparagus plants.
Physical Characteristics: Asparagus thrips are about one millimeter long with two pair of fringed wings. Immature thrips are wingless and lighter in color.
Behavior: Thrips puncture plants with their sucking mouthparts and feed on the plants moisture.
Damage: Thrips suck the moisture from asparagus ferns resulting in distorted fern growth. They may look ragged, turn yellow, and become shortened and twisted.
Management: Controlling weeds in the garden is the main method of thrip management. If the infestation is severe, more aggressive measures may become necessary.
“Aphid, Asparagus.” University of Massachusetts Amherst. N.p., n.d. Web. 26 Feb. 2014. <http://extension.umass.edu/vegetable/insects/aphid-asparagus>.
“Asparagus – An Early Spring Treat.” Asparagus –. N.p., n.d. Web. 26 Feb. 2014. <http://www.wvu.edu/~agexten/hortcult/homegard/spgasparg.htm>.
“Asparagus Beetle.” University of California Agriculture & Natural Resources. N.p., n.d. Web. 26 Feb. 2014. <http://www.ipm.ucdavis.edu/PMG/r7300511.html>.
Dan, Drost. “Asparagus in the Garden.” Utah State University Extension. N.p., n.d. Web. 26 Feb. 2014. <http://extension.usu.edu/files/factsheets/asparagus.pdf>.
“European Asparagus Aphid.” University of California Agriculture & Natural Resources. N.p., n.d. Web. 26 Feb. 2014. <http://www.ipm.ucdavis.edu/PMG/r7300111.html>.