Autographa precationis Guene Lepidoptera Noctuidae

Natural History

Distribution. This native species is eastern in distribution. It is found widely in the United States east of the Great Plains, though it is infrequent in the southernmost states. Occasionally, plantain looper is found as far west as Kansas, Nebraska, and Wyoming. Similarly, in Canada it is known from Nova Scotia to Manitoba.

Host Plants. This insect sometime feeds on such vegetables as bean, cabbage, and parsnip, but is more commonly associated with such weeds as burdock, Arctium lappa; common morningglory, Ipomoea purpurea; dandelion, Taraxacum officinale; lambsquarters, Chenopodium album; plantain, Plantago spp.; thistle, Carduus sp. and Cirsium sp.; wild lettuce, Lactuca sp.; and wild sunflower, Helianthus sp. It has also been found feeding on hollyhock.

Natural Enemies. Natural enemies of this insect are unknown.

Life Cycle and Description. Larvae are the overwintering stage, and apparently there are 2-3 generations annually (Knutson, 1944; Chapman and Lienk, 1981). Moths are present in New York from May until November with a reduction in abundance near the end of June, which probably signifies the completion of the first generation (Chapman and Lienk, 1981). A complete life cycle requires about 30-37 days for completion (Khalsa et al, 1979).

  1. The egg stage of this little-known insect seems to be undescribed.
  2. The number of instars usually is six, but occasionally seven are observed. Head capsule widths are about 0.3, 0.5, 0.7, 1.0, 1.3, 2.0, and 2.7mm for instars 1-7, respectively. Total duration of the larval stage is 17-20 days, with the length of individual instars being about 3.0, 3.0, 2.0, 3.5, 2.8, and 2.3 days, respectively, for instars 1-6. The mature larva is green and, like most of the other loopers, bears three white lines on each side of the back and a white lateral line slightly above the lateral spiracles. The white lines are pale in overwintering larvae but distinct in summer larvae. There tends to be dark shading above the lateral line. The body appears to lack microspines, but there is at least a subdorsal strip of these minute structures. The thoracic legs generally are black. The head bears a broad black line on each side; sometimes the lines are broad and cover the entire head. The larva measures about 30 mm long at maturity. This insect closely resembles alfalfa looper, Autographa californica, and bilobed looper, Megalographa biloba, in appearance, and is reliably distinguished by examination of the larval mandibles (see Crumb, 1956, or Eichlin and Cunningham, 1978 for a key). However, the geographic range is generally adequate for differentiation from alfalfa looper, and if microspines are readily apparent there is great likelihood that it is bilobed looper.
  3. Duration of the pupal stage is about 6-7 days.
  4. The moth is similar to alfalfa looper in general appearance, with the forewing bearing a silvery white central spot shaped roughly like a "dog leg." However, the "foot" is weakly connected to the "leg," or even disconnected, in plantain looper. The background color of the forewing varies from gray to dark-brown. The hind wing is light brown basally and light to dark-brown distally. The wingspan of this moth is about 35 mm. Mating typically occurs about two days after emergence from the pupa. Females oviposit over a period of about 14 days and produce over 2000 eggs per female. Total adult longevity is estimated at about 19 days.

Key elements of the biology of this insect can be found in Khalsa et al. (1979), with additional information and keys in Crumb (1956), Eichlin and Cunningham (1978), and Chapman and Lienk (1981). A key to some common vegetable-feeding loopers, including plantain looper, can be found in Appendix A.

Damage

This insect feeds on the underside of leaves during the first three instars, causing a skeletonizing effect. Thereafter, larvae eat large, irregular holes in leaves. Khalsa et al. (1979) demonstrated that this insect consumed almost as much as the more damaging soybean looper, Pseudoplusia includens. However, few plantain loopers are usually found attacking crops, so oviposi-tional preference keeps this insect from becoming a serious pest.

Management

Moths of this species are attracted to light traps. They also can be captured in traps baited with phenylacetal-dehyde (Cantelo et al., 1982). This insect normally does not warrant suppression. Foliar insecticides are effective, if needed.

Adult plantain looper.
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