Corimelaena pulicaria Germar Hemiptera Thyreocoridae

Natural History

Distribution. This common native insect is found throughout the United States and southern Canada, except possibly the Maritime Provinces of Canada. Its distribution also includes Central America. In the western United States a related and similar-appearing species, C. extensa Uhler, occasionally feeds on crops.

Host Plants. This insect has been observed feeding on many plants. Among vegetables attacked are celery, potato, and sweet potato. It has also been associated with field crops such as chufa, clover, soybean, and sugarbeet. It is probably best known for damage to small fruits such as blackberry, grape, raspberry, and strawberry. Weeds are common hosts, incuding beggarstick, Bidens spp.; ragweed, Ambrosia spp.; redroot pigweed, Amarnathus retroflexus; wild carrot, Daucus carota; wild chervil, Cryptotaenia canadensis; plantain, Plantago lanceolata; common mullein, Verbas-cum thapsus, and others. Weeds appear to be preferred hosts.

Natural Enemies. Natural enemies seem to be unknown.

Life Cycle and Description. There is a single generation per year in the northern United States. The adult is the overwintering stage. Adults seek shelter under leaf litter and boards during the winter months. The adults are active early in the year, and eggs are deposited in May and June. Nymphs are found throughout the summer months.

  1. The eggs are deposited singly. They are oval in shape and orange to red in color and measures about 0.6 mm long and 0.4 mm wide. Incubation is about 10-14 days.
  2. The young nymphs greatly resemble the adults, but the abdomen is colored red. There are five instars. Development time for the nymphs is about 30 days. Because the overwintered adults live through much of the summer and continue to oviposit, overlapping stages of development are found during the summer.
  3. The adults are oval in overall form, and greatly resemble beetles. Examination of the mouth-parts quickly separates the two groups, however, as the piercing-sucking mouthparts of the negro bug are easily observed. The scutellum of these insects, and other members of the family, are greatly enlarged and bluntly rounded, covering nearly the entire abdomen. This effectively hides all but the leading edge of the wings. Where the wings are exposed, along the perimeter of the abdomen, there is a whitish stripe. As its name suggests, the insect is almost entirely black, the principal exception being the aforementioned edges of the wings. This bug is quite small, and measures only 2.2-3.5 mm long. The antennae
Corimelaena Pulicaria
Adult negro bug.

are five segmented, and the mouthparts consist principally of a four-segmented labium.

The biology of this insect is poorly documented. Partial life histories were provided by Riley (1870a) and Davis (1893). McPherson (1982) gave a good summary, especially of host-plant records, and keys for identification. A key to distinguish stink bugs (including Negro bug) commonly affecting vegetables also is found in Appendix A.


This generally is a minor pest, but it does reach high numbers on occasion. On celery, the bugs are known to aggregate into small clusters and feed at the joint where the leaf petioles meet the stem. This causes the terminal leaves to wilt and die. The bugs then move progressively lower on the plant until even the youngest tissue is destroyed. In addition to its feeding injury, it is reputed to have a foul odor, and by walking on fruit, to impart a disagreeable taste (Riley, 1870a).


These insect are infrequent pests, and are readily controlled with foliar applications of insecticides. Because little negro bugs feed predominantly on weeds, it is a good idea to keep weeds under control, or at least well-separated from vegetable and berry crops.

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  • Clotilde
    Does thyreocoridae live in the winter?
    8 years ago

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