''Chilocorus stigma'', commonly known as the twice-stabbed ladybug, is a native resident of the

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...

and

Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by tot ...

but does not live west of the

Sierra Nevada The Sierra Nevada () is a mountain range in the Western United States, between the Central Valley of California and the Great Basin. The vast majority of the range lies in the state of California, although the Carson Range spur lies primarily ...

.. It also has been introduced to

Hawaii Hawaii ( ; haw, Hawaii or ) is a state in the Western United States, located in the Pacific Ocean about from the U.S. mainland. It is the only U.S. state outside North America, the only state that is an archipelago, and the only stat ...

. It is shiny black, and there is one red spot on each

elytron An elytron (; ; , ) is a modified, hardened forewing of beetles (Coleoptera), though a few of the true bugs (Hemiptera) such as the family Schizopteridae are extremely similar; in true bugs, the forewings are called hemelytra (sometimes alterna ...

. The remainder of the body is black as well, but the abdomen is either yellow or red. It is sometimes confused with the "two-stabbed lady beetle", ''

Chilocorus orbus ''Chilocorus orbus'' is a species of lady beetle in the family Coccinellidae. It is native to North America. It is a black, domed beetle with two large red spots and is commonly called the twice-stabbed lady beetle. Both adults and larvae feed o ...

'', which is widespread in California.

Habitat and pests eaten

''C. stigma'' mainly lives within terrestrial/arboreal habitats, primarily feeding on

aphid Aphids are small sap-sucking insects and members of the superfamily Aphidoidea. Common names include greenfly and blackfly, although individuals within a species can vary widely in color. The group includes the fluffy white woolly aphids. A t ...

s found in these habitats as well as

scales Scale or scales may refer to: Mathematics * Scale (descriptive set theory), an object defined on a set of points * Scale (ratio), the ratio of a linear dimension of a model to the corresponding dimension of the original * Scale factor, a number w ...

(such as pine needle scale, beech bark scale and Florida red scale) and

mealybug Mealybugs are insects in the family (biology), family Pseudococcidae, unarmored scale insects found in moist, warm habitats. Many species are considered pest (animal), pests as they feed on plant juices of greenhouse plants, house plants and sub ...

s. It is a beneficial insect, and is useful in both natural wood stands and commercial forests such as

orchards An orchard is an intentional plantation of trees or shrubs that is maintained for food production. Orchards comprise fruit- or nut-producing trees which are generally grown for commercial production. Orchards are also sometimes a feature of larg ...

and

citrus ''Citrus'' is a genus of flowering plant, flowering trees and shrubs in the rue family, Rutaceae. Plants in the genus produce citrus fruits, including important crops such as Orange (fruit), oranges, Lemon, lemons, grapefruits, pomelos, and lim ...

groves. It is beneficial against non native species. An introduced Hemlock pest, the elongate hemlock scale (''Fiorinia externa'' Ferris), which has been doing considerable damage to Hemlock trees throughout North America, can be moderately controlled by the presence of ''C. stigma''. ''C. stigma'' is currently not a lady beetle that can be sold for commercial use in orchards or on farms.

Life cycle and issues

''C. stigma'' usually completes two lifecycles a year in Canada and the North United States but may complete several lifecycles a year further down South. They overwinter in ground litter during the colder months. ''C. stigma'' has been shown, like other ladybeetles, to be susceptible to the use of

insecticide Insecticides are substances used to kill insects. They include ovicides and larvicides used against insect eggs and larvae, respectively. Insecticides are used in agriculture, medicine, industry and by consumers. Insecticides are claimed to b ...

s diminishing its population in the wild. In order to preserve the benefits of this insect, pesticide users are encouraged to use natural alternatives to pesticide in order to curb the decline of ''C. stigma''.

Chromosome variation

The chromosomes (

karyotype A karyotype is the general appearance of the complete set of metaphase chromosomes in the cells of a species or in an individual organism, mainly including their sizes, numbers, and shapes. Karyotyping is the process by which a karyotype is disce ...

) of ''Chilocorus stigma'' vary from one individual to another, in both the number of chromosomes (

aneuploidy Aneuploidy is the presence of an abnormal number of chromosomes in a cell, for example a human cell having 45 or 47 chromosomes instead of the usual 46. It does not include a difference of one or more complete sets of chromosomes. A cell with any ...

) and their structure (

chromosomal polymorphism In genetics, chromosomal polymorphism is a condition where one species contains members with varying chromosome counts or shapes. Polymorphism is a general concept in biology where more than one version of a trait is present in a population. In ...

). The variability occurs as a result of chromosome fusions or disassociations.White M.J.D. 1973. ''The chromosomes''. Chapman & Hall, London. p169

References

External links

Detailed information on ''C. stigma''
{{Taxonbar, from=Q5099147 Coccinellidae Biological pest control beetles Insects used as insect pest control agents Beetles described in 1835