Popillia japonica
Geographic Range
Japanese beetles are native to east Asia; however, they were accidentally introduced into the United States in 1916 (Encyclopedia Britannica Online). In North America they occur from Georgia west to Missouri, north to Ontario and east to Nova Scotia, with some populations now in California (NC Co-op Extension Service).
Habitat
Japanese beetles can apparently live anywhere there is sufficient foliage to feed on. They are not limited to forests or grasslands, but often live on farms, cities, and even your garden.
- Terrestrial Biomes
- savanna or grassland
- forest
Physical Description
Like all beetles, Japanese beetles have a hard exoskeleton and chewing mouthparts (Barnes, 1987). The adult beetle is 10-12 mm long with a metallic body (usually green or copper) and bronze wing covers (Fleming, 1972). These hardened wing covers are actually modified wings called elyptra (Meglitsch andSchram, 1991).
The Japanese beetle egg is white and almost translucent. It's shape is spherical and it is about 2 mm in diameter(www.ncsu.edu, 1).
The larvae are white grubs with a grayish cast to them because of the aggregation of soil and fecal material in their hindgut. They have a dark brown head and three pairs of legs. They are characterized by their "C"-shape form, grow to be about an inch long, and can be distinguished from other larvae by their "V"-shaped pattern of spines underneath their abdomen (Grupp, 1).
The pupa is usually 13 mm long and tan colored right up until the adult emerges, when it turns metallic green. Its appendages are pressed to the body, but otherwise it resembles the adult form(www.nscu.edu, 1).
- Other Physical Features
- ectothermic
- bilateral symmetry
Reproduction
Japanese beetle have one complete life cycle that lasts an entire year. In mid-summer, the adult beetles emerge from the pupal stage. During warm days, the beetles fly and congregate on host plants to feed and, more importantly, mate. After mating, that afternoon the females deposit one to four eggs in loose, moist soil. In the female beetle's life, she will produce 40-60 eggs. Two weeks after the eggs were deposited, the larva emerge. They feed on the fine roots of grass-like plants and remain active until cold weather, when they "hibernate" under the soil surface. When the soil warms up again in the spring, the larva move closer to the surface and resume feeding. Soon after that, the grubs remain inactive for a 10-day period until pupation begins. The pupal stage lasts for 8 to 20 days, then the adults emerge (North Carolina Extension).
Behavior
Japanese beetles travel and feed in groups. A swarm of beetles have been known to strip a peach tree in 15 minutes, leaving behind only bare branches and the fruit pits (Encyclopedia Britannica Online).
Food Habits
Japanese beetles are known to feed on a variety of trees, shrubs, grasses, and nursery plants. The adults feed on the flowers, fruit, and leaves of the such plants as grapes, peach, rose, cherry, soybea, hibiscus, Indian mallow, dahlia, zinnia, horsechestnut, willow, elder, and sassafras(NC Coop Extension).
The larva feed on the roots of grass-like plants while they overwinter(Encyclopedia Britannica Online).
Economic Importance for Humans: Negative
Japanese beetles are pests of agriculture and horticulture. especially in North America.
Conservation Status
This species is not protected, and in North America measures are being taken to control the spread of this pest. Insecticides kill adult beetles, but do not prevent reinfestation. Some of the beetle's natural predators such as wasps and flies have been imported from Japan to help control the population. Moles, shrews, skunks, and birds also significantly decrease the population by eating the larva form. Biological control is available using a bacterium, Bacillus popilliae, which causes milky disease in the larvae--thereby greatly reducing Japanese beetle populations (Encyclopedia Britannica Online, NCCES, Grupp).
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- IUCN Red List
- No special status
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- US Federal List
- No special status
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- CITES
- No special status
Contributors
Shivawn Bilberry (author), Southwestern University, Stephanie Fabritius (editor), Southwestern University.
Glossary
- Nearctic
-
living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.
- bilateral symmetry
-
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
- ectothermic
-
animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature
- forest
-
forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.
- introduced
-
referring to animal species that have been transported to and established populations in regions outside of their natural range, usually through human action.
- native range
-
the area in which the animal is naturally found, the region in which it is endemic.
- oriental
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found in the oriental region of the world. In other words, India and southeast Asia.
- tropical savanna and grassland
-
A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.
- savanna
-
A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.
- temperate grassland
-
A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.
References
""Japanese beetle" Encyclopedia Britannica Online" (On-line). Accessed March 27, 2000 at http://search.eb.com/bol/topic?eu=44344&sctn=1&pm-1.
Barnes, R. 1987. Invertebrate Zoology, 5th ed.. Philadelphia: Saunders College Pub..
Fleming, W. 1972. Biology of the Japanese Beetle. UsDA Tech.
Grupp, S. "The Bug Review-Japanese beetle" (On-line). Accessed April 3, 2000 at http://www.urbanext.uiuc.edu/bugreview/japanesebeetle.html.
Meglitsch, P., F. Schram. 1991. Invertebrate Zoology, 3rd ed.. New York: Oxford University Press.
North Carolina Cooperative Extension Service, "Soybean Insect Notes: Japanese Beetle" (On-line). Accessed April 3, 2000 at http://ipmwww.ncsu.edu/AG271/soybeans/japanese_beetle.html.