Insect Note #35 (Revised)

Dated 6/93
Placed on the Web 4/95 by the Department of Entomology, NCSU

Asparagus Insects and Their Control

Insects damage asparagus by their presence of feeding on the tender spears, stems and ferns. Those occurring on spears and later on ferns are of most importance and concern to the grower, the processor, and the consumer.

Two critical periods exist when insect damage is paramount. Early season presence of asparagus beetles, grasshoppers, and cutworms on spears must be prevented, and early detection and control of such late-season foliar pests as armyworms and aphids must receive attention if maximum growth for next year's crop is to be achieved.

The following key is provided to assist with the diagnosis of insect problems:

Key for the Recognition and Identification of Pests of Asparagus

1. • Insects and/or damage present on spears --- 2
     
   • Insects and/or damage present on foliage, terminals may be curled, wilted, discolored or dead --- 4
   • Stems girdled, yellow, or dead --- 13

2. • Spears and shoots with large holes, plump, smooth brownish caterpillars up to 1-1/2 inches long may be seen lying curled up on their sides in the soil --- CUTWORMS (Black Variegated)
     
   • Spears or shoots scarred --- 3

3. • Feeding scars small, if present, adult insects brightly colored blue, red, and yellow about 14 inches long and larvae are dull gray, humpbacked, and sluggish. Bullet-shaped eggs are about 1/16 inches long, dark brown, and are laid in rows along spears and stems --- ASPARAGUS BEETLE
     
   • Feeding scars larger, spears may be curved, damage usually begins at field margins, insects may or may not be present --- GRASSHOPPERS

4. • Foliage removed, stems scarred causing terminals to appear whitish --- ASPARAGUS BEETLE
     
   • (See first alternative in #3 above) or adults are 1/4 inch long, light brown to reddish- orange with 6 small black spots on each wing cover. Larvae are up to 3/8 inch long, humpbacked, wrinkled and yellow to orange, and feed mostly on berries -- SPOTTED ASPARAGUS BEETLE
     
   • Foliage damage not as above --- 5

5. • Foliage consumed, webbing may be present --- 6
     
   • Shoots wilted, curled, dead, or stunted with tufted ferns --- 11

6. • Foliage stripped or consumed by dark green and coppery beetles about 1/2 inch long, usually appearing in large numbers in June or July --- JAPANESE BEETLE

7. • Foliage ragged and sometimes entirely consumed, stems scarred injury beginning around field margins --- GRASSHOPPERS
     
   • Foliage consumed by caterpillars, webbing may be present - -- 8

8. • Foliage webbed, pale green caterpillar with brown head living within tied leaves --- Sparganothis sulfereana
     
   • Foliage consumed but not fitting above description --- 9

9. • Foliage consumed by striped, light green caterpillars up to 1 3/4 inch long with a pair of dorsal triangular black markings on most segments and a yellowish-orange stripe in each side --- CABBAGE LOOPER
     
   • Foliage stripped or consumed by caterpillars not fitting above description --- 10

10. • Foliage stripped and often webbed by caterpillars up to 1 3/4 inch long with a pair or dorsal triangular black markings on most segments and a yellowish-orange stripe in each site --- YELLOW-STRIPPED ARMYWORM

11. • Shoots stunted, blue gray in color (Bonsai effect), tufted ferns present when insect population is high. Insects colonize the axils the ferns and are small powdery, gray-green soft-bodied without cornicles --- ASPARAGUS APHID
      
    • Shoots wilted, curled, brown or dead --- 12

12. • Terminal shoots wilted, curled or dead, small soft-bodied, green or pink insects feeding in groups are present --- APHIDS (Bean, Melon, Potato)
      
    • Shoots wilted or brown, active, flat-backed sucking bugs may be present --- PLANT BUGS (Stink, Tarnished Plant, Harlequin Bugs or Garden Fleahopper

13. • Trails on stems and girdling caused by whitish, legless and headless maggots up to 1/4 inch long mining beneath the epidermis of stems, usually near the base of plants. Adults are small, black, shiny, two winged flies, 1/6 inch long --- ASPARAGUS MINER

Please refer to the following table for specific insecticide selection. Also, remember that the need, time and selection of insecticides are critical, if desired control of insect pests of asparagus is to be achieved. Also, follow label directions closely as severe plant damage may result from improper application.

Table: Relative Effectiveness of Various Insecticides Against Asparagus Insects.

For specific chemical control recommendations see the most recent N. C. Agricultural Chemicals Manual.