Field Guide     Pest Management     Grape Colaspis

Grape Colaspis

CROPS IMPACTED: corn, soybean

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Family: Chrysomelidae

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About the Grape Colaspis

Reproduction and Life Cycle

Once cooler weather hits, the larvae of the grape colaspis will move to about 8 inches below the soils surface and feed on plant roots. This is where they will overwinter as a partially developed larva (usually in the third instar). Once spring comes, they will begin feeding again on roots and complete their 8 instars. They will then pupate about 3cm beneath the soils surface. This process will last between 3 and 7 days leading to the adult’s emergence, often occurring in June. The beetles will then mate and eat for about 4 days, after which, they lay their eggs. Eggs are placed in clusters of approximately 35 around the roots of host plants. There is only 1 generation per year.

Grape Colaspis Identification and Habitat

Identification

The adult grape colaspis is an oval shaped beetle that is yellow-brown and 4 or 5mm in length. The wing covers have shallow indentations in rows that give the beetle a striped appearance. The egg is white or yellow, has a smooth texture, and is 0.6mm long and 0.25mm wide. The larvae are about 7mm in length, are anywhere from gray to white to tan and have a dark coloured head. They resemble a grub with 3 sets of legs close to the head and have appendages attached to each segment of the abdomen. The pupae are white in the beginning, and will darken as they mature. Typically they are around 4mm long.

Habitat

The grape colaspis is a common pest in the eastern United States, preferring soil that is not properly drained, non-rotated, and organic. They mainly feed on foliage, but often do not cause a significant amount of damage. However, under high populations, the damage can usually be noted by stunted and yellowing plants. This is from the larvae feeding on the plants roots and the outer tissues of the piece of stem that is in the soil. The adults feed on the foliage, often with larvae eating the roots of the identical plant. They prefer soybean and corn plants; however, they can also be found on grape, white and red clover, beet, snap pea, and more.

Grape Colaspis Management and Control Methods

Cultural Control

In order to control the grape colaspis, it is best to use prevention methods to avoid an infestation in the first place. Plant your seeds at the same time so that all seedlings will emerge within a similar timeframe. Also, promote vigorous root growth by using proper fertilization and irrigation methods. This can help the plants to become strong before the grape colaspis has a chance to injure it. Plan to rotate out soybeans and corn from time-to-time to deter this pest from entering your field; having a different crop in its place that the colaspis will not feed off of can greatly suppress their population. However, it is important to note that having satisfactory control is often dependent on using an integrated management system that includes the use of cultural and chemical methods.

Chemical Control

In using chemical control for the grape coaspis, the insecticide zeta-cypermethrin is sometimes used on corn. For soybeans, acephate, and pyrethroids have been known to be successful. Once again, be aware that this pest does not generally cause enough damage to warrant a chemical treatment, so exercise caution before application. If you do feel that this pest has surpassed the economic threshold, be sure to carefully read the label for proper application. It is extremely important to never spray on days that are windy. After applying insecticides, it is important to irrigate sprayed area to increase the insect control.

Latin / Alternative Grape Colaspis Names

  • - Colaspis brunnea

Sources

http://ipm.ncsu.edu/AG271/soybeans/grape_colaspis.html

http://bulletin.ipm.illinois.edu/pastpest/articles/200311b.htm

http://lib.dr.iastate.edu/cgi/viewcontent.cgi?article=2379&context=rtd