Mexican bean beetle
| Mexican bean beetle | ||||||||||||
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Mexican bean beetle ( Epilachna varivestis ) |
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Epilachna varivestis | ||||||||||||
| Mulsant , 1850 |
The Mexican bean beetle ( Epilachna varivestis ) is a beetle from the Epilachnini tribe of ladybirds . This group mainly includes herbivorous species.
features
The beetles have an oval shape and are about 6 to 7 millimeters long. The males are slightly smaller than the females. They are straw-colored or creamy yellow in color. In young animals, eight black dots are visible on each wing , which are arranged in three rows. Older animals become darker until they turn bronze in color. During this time, the points also disappear. The newly hatched larvae are light yellow in color and reach a maximum length of 1.6 millimeters. They have branched spines that are arranged in six rows. These are also light yellow at first, but a few hours after moulting at the tips, they become darker and therefore more noticeable. Adult larvae are 6 to 9.5 millimeters long and have a greenish-yellow color. The eggs are light yellow to orange-yellow in color and are 0.6 millimeters wide and 1.3 millimeters long.
Occurrence
The original range is likely to be the plateau in southern Mexico. From there, the species spread across Mexico and most of the United States east of the Rocky Mountains . To the south their distribution extends to Guatemala , to the north to the New England states and southern Canada . In 1933 it was reported that the species had been exterminated in Florida , but it was found there in 1938 and has been firmly established again since 1942.
Way of life
The female lays 500 to 600 eggs, which are carefully pinned to the underside of leaves in groups of 40 to 75 so that they are vertical. In warm weather the larvae hatch after a week, in bad weather after two weeks.
The first hatched larvae stay together and feed on the leaf on which they hatched. If the leaf is dry, they will also eat the remaining eggs. When the larvae get older, they split up into smaller groups. During pupation, the larva clings to various plants and pupation can take from 5 to 10 days. The adults are good fliers, which helps them to find food. The beetles start looking for leaves in autumn to hibernate in. They usually rest until spring, but hibernation can last longer.
The beetle as a pest
This beetle belongs to the herbivorous species of ladybirds. It is considered a pest because the larvae in particular eat large amounts of plant material. Larva and imago feed on useful and ornamental plants .
As a fight z. B. Podisus maculiventris from the family of stink bugs , but also the fly epilachnae Paradexodes and the Wasp Pediobius foveolatus be for biological pest control used.
Web links
- Description page of the Department of Entomology and Nematology of the University of Florida (Engl.)