The European corn borer is a lepidopteran and a moth of the family Crambidae. The European corn borer is also known as the European high-flyer or the European corn worm. The European corn borer is highly variable in look. It often invades grass stems in undisturbed pastures and different corn varieties. The European corn borer is an introduced species that is a grain pest, especially on the corn. The corn borer represents a diversified feeding behavior and breaks corn tassels, and it's boring into the stalks may collapse them. They also chew on leaves and bore into corn ears reducing their marketability. It is also the most extensively studied pest, and over 1000 published researches only encompass the European corn borer alone. Besides, devastating corn, the European corn borer also feeds on peppers, cotton, apples, and soybean. The European corn borer is pervasive in entire corn-growing regions of the US. The US growers spend more than 1 billion dollars annually to manage the European corn borer.
The European corn borer is native to Europe and probably introduced into the US with imported corn from Hungary and Italy. The European corn borer was initially perceived in Boston in 1917 and near Lake Erie in 1921. A gradual spread brought it into northern Ohio from southern Michigan. In Western Michigan, it spread up to Wisconsin Shore in 1938. The European corn borer emerged as two generations per annum pest in north-central and eastern states by the end of the 1930s. It developed speedily and emerged as a dominant corn pest in the US central belt. Later it reached Illinois, Iowa, and Nebraska in 1939, 1942, and 1944, respectively. In North America, the European corn borer is now an established pest in eastern Canada and every U.S. state in the east of the Rocky Mountains.
Adult females are light yellowish-brown having uneven bands of darker wavy lines across the wings. Adult males are darker than females having lime brown wings. Eggs are laid in clusters of 5 to 50. Initially, the eggs are oval and white but turn yellowish later in the developmental process present on the undersides of the leaves. The average length of the eggs is about 1.0 mm that hatch in between 5 to 9 days. Larvae are yellow having several dotted brown lines. Fully-mature larvae measure up to 25 mm in length with fainted spots on the dorsal surface and variable in color.
The larvae of the European corn borer overwinter under crop stubbles and grasses roots. The larvae appear in early spring. Moth flies and oviposits in early to mid-summer in those areas that usually host one or two generations, annually. The average hatching time remains 7-days after the eggs. The larvae complete 6-instars in around 50-days and pupate for almost 12 days which is entirely temperature-dependent. An average pre-oviposition period is almost 3.5-days, and it continues for another 14 days. A female lays up to 50 eggs per day and 400 to 600 during the entire lifecycle. The adults survive between 3 to 4 weeks. They may have 2 to 4 generations that vary from one generation in the northern climate to 4 in southern locations.
The European corn borer is a serious pest of all strains of corns except Bt. The larvae of the European corn borer feed on tassels, ear shoots, leaf sheath, stalks, and kernels during different instar as they molt from the first instar to 6th instar. Sometimes, they heavily feed on cobs and bore into the stalks. They may leave bore entry and exit holes on the cobs, and their frass attracts blotch and other bacterial diseases. Mature larvae bore the bigger size holes in corn stalks and combs, But, boring by the initial larval stages could also break tassels. Their feeding in a tunneling pattern spoils the quality and reduces corn production to exponential levels. Other than corn, European corn borers harm fruits and pods in peppers, beans, and cowpea.
The European corn borers emerge from plant debris and crop stubbles where they overwinter. After pupation, they lay eggs on the plant surfaces. The larval stages continue after that are more damaging than the adult flyers. Look for them in early summer and check the boreholes in corn stalks, tassels, and combs.
Besides following all preventions and cultural practices if the European Corn Borer damage remains prevalent on corn, here are the most proven ways to suppress their population using the biological, organic, and chemical methodologies;
Monterey Bt contains 98.35% of the Kurstaki strain of Bacillus Thuringiensis, and Bt application on European corn borers produces toxin proteins in their bodies. Infecting European corn borers with Bt leads to prolonged control in the garden. The gardeners may find 6 million active Bt spores per gram of the product concentrate and it is more effective than many insecticides. Since most gardeners don't wish to plant Bt-Corn, Bacillus Thuringiensis when applied for biological pest control is acceptable as it leaves no harm on the crops, humans, and the environment. The gardeners may repeat Bt applications if they're in a multiple-generation area.
Monterey B.t. - Biological Insecticide for Organic Gardening - 1 Pint Concentrate - Apply Using a Sprayer Following Mix Instructions
Add 1 teaspoon of Monterey Bt per gallon of water and apply on corn in the evening.
When released in a garden, mature Trichogramma wasps lay eggs on the eggs of European corn borers. After hatching, the wasp larvae feed on the embryos of the borers. As a result, European corn borer eggs fail to hatch and turn black as wasp larvae capture the resources of the larvae of the borer. Usually, Trichogramma wasps live for about 7 or 10 days, and their multiple generations not only feed on the European corn borer eggs. This keeps their population suppressed till the wasps keep on multiplying on your garden corn. It keeps the borers' population checked and never lets them bore into corn stalks and combs.
Orcon TR-C3SQ Live Trichogramma, 3 Squares/12,000 Eggs
Each square contains about 4000 eggs, and 12000 eggs are available in 3-squares. 3 to 5 five eggs can have applied per square foot of the European corn borer infected area.
This insect killer combines Potassium Salts of Fatty Acids with Pyrethrins, and it remains ideal for spot spraying of European corn borers in an organic garden. The product is ready to use, and both ingredients are present in 1.015% and 0.012% by weight in the mixture, respectively. The insecticide applications during two critical periods are more helpful. These applications must target once when the corn tassels emerge and again during the fresh silk stage. The spot spraying targets must remain whorl and silks, not the entire plant structure.
Safer Brand 5085-6 Tomato & Vegetable Insect Killer, 32 oz
Insect killer can also apply to peppers, soybeans, cowpeas, chickpeas, and peas, where European corn borer infestations occur from spring through summer.
Garden Safe- Insect Killer contains 85% Silicon Dioxide which is the finest grade Diatomaceous Earth that derives from the fossilized resources. Diatomaceous Earth works excellently against all larval stages of European corn borers. It stops molting, and the crawlers injure themselves when they contact DE. Direct injury results in dehydration of the larvae, and they die at the spot, and DE's fine and sharp edges don't allow them to relocate. DE is always OMRI-listed and doesn't contain any synthetic traces and killing results due to the physical misadventure of the European corn borer larvae.
Garden Safe Brand Crawling Insect Killer Containing Diatomaceous Earth, 4 Pounds, Kills Cockroaches, Ants and Other Listed Crawling Insects by Contact, For Use Indoors & Outdoors
DE applies as a physical barrier around the stems of the plants and on the foliage if infestations exceed.
The Garden Insect Spray contains 0.5% Spinosad, derived from Saccharopolyspora Spinosa fermentation, and holds a unique mode of action. Spinosad contains Spinosyn A and Spinosyn D, and it is approved for organic status since 2003 by USDA- National Organic Program. This concentrate is OMRI listed and effective against the entire larval stages of the European corn borers. Spinosad is best sprayed in the evening for the effective control of borers that mostly feed during the initial five hours after sunset. This concentration is also safe for humans, and the environment provided it dries out before entering the garden.
Monterey LG6150 Garden Insect Spray, Insecticide & Pesticide with Spinosad Concentrate, 16 oz
Depending on the types of infestations, mix 1 to 2 ounces of the product concentrate per gallon of water and apply to the corn foliage from late spring to mid-summer when laying peaks.
Due to the variable regulations around (de)registration of pesticides, your national list of registered pesticides or relevant authorities should be consulted to determine which products are legally allowed for use in your country when considering chemical control. Pesticides should always be used lawfully, consistent with the product's label.
Check out our other guides on common garden bugs.
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