Orthops scutellatus Uhler Hemiptera Miridae

Natural History

Distribution. Carrot plant bug is native to Europe, where it is widely distributed. In North America, it was first discovered in New York in 1917, and since then it has spread throughout southern Canada and the northernmost states of the United States. The exception is the Rocky Mountain region, where this insect has spread southward, at high elevations, as far south as Arizona. This is a fairly common pattern of distribution for cold-adapted insects.

Host Plants. Carrot plant bug is restricted to the plant family Umbelliferae. Vegetable crops attacked are carrot, celery, parsnip, and parsley. It also feeds on dill, and on many wild umbelliferous plants such as poison hemlock, Conium maculatum; wild carrot, Daucus carota; and wild parsnip, Pastinaca sativa. In

Massachusetts, this plant bug was reported to prefer celery over other plants. Unlike tarnished plant bug, Lygus lineolaris (Palisot de Beauvois), with which it is often associated, it prefers crops over weeds.

Natural Enemies. Natural enemies are not well-known. General predators such as lady beetles (Coleoptera: Coccinellidae), and likely many other insects, prey on the nymphs, but this has not been established.

Life Cycle and Description. There are three generations annually in Massachusetts. Duration of the life cycle, from egg to adult, is 6-7 weeks. This insect overwinters in the adult stage, hidden among weeds and tall grass. Adults emerge from overwintering in May, and egg laying occurs in early June, mid-July, and early September.

  1. The eggs are deposited in the buds and other young tissue. They typically hatch in 4-10 days. The number of eggs produced per female is not known to exceed 48, but this seems to be inordinately low, and likely represents the consequences of feeding on an unsatisfactory diet.
  2. Young nymphs are pale green. There are five instars. Duration of the nymphal stage requires about 32-34 days, with about 6.7, 3.5, 5.0, 5.3, and 12.3 days required for instars 1-5, respectively.
  3. The adult bug is quite distinctive in color, and readily separated from tarnished plant bug, Lygus lineolaris, with which it commonly co-occurs. Carrot plant bug is light-brown, but marked with dark-brown bands crossing the front wings (hemelytra). The scu-tellum is yellow, and surrounded by dark-brown. The legs are yellow basally, but become brownish to black distally.
Green Insect With Yellow And Black Legs
Adult carrot plant bug.

The only biological research conducted on this insect in North America was given by Whitcomb (1953). Henry and Froeschner (1988) gave a good account of geographic distribution.

Damage

This is a common plant bug on umbellifers, but damage is often trivial, or limited to seed crops. It is not considered to be a pest of commercial crops in North America, though in the past it did cause appreciable damage to celery in Massachusetts. Adults and nymphs feed on sap from leaves, buds, and seeds. In Massachusetts, carrot plant bug was shown to damage celery by feeding on the stalks; a darkening and destruction of the tissue, followed by invasion of plant pathogens, was associated with feeding by these plant bugs. Stunting of the plants also was reported.

Management

There generally is little need for control of this insect. Only when it first gained entry to North America was it observed to attain pest status. However, Whitcomb (1953) considered that population densities as low as one bug per 10 celery plants could produce damage. Carrot plant bug is readily suppressed with foliar insecticides, including botanicals.

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