Monday, December 22, 2008

March of the Millipedes!

Due to the cold weather, we might notice another animal crawling indoors, a millipede. The adult millipedes overwinter in protected areas, so we may see them inside structures, such as greenhouses or homes. Millipedes in Texas are typically brownish in color, but can vary from red to yellow to orange. Their bodies are rounded in shape and they have four legs per body segment. Most species are less than ½ inches in length, but the species in west Texas can be up to 4 inches in length. Another characteristic of millipedes is they curl into a spiral to protect themselves when disturbed.

In the spring, the millipedes become active and the females of some species will lay eggs in the soil, while other species will give birth to living young. The immature millipedes are smaller in size with fewer legs compared to the adults. Additional segments are produced after each molt, so the millipede grows in size. Millipedes usually develop into adulthood within 21 to 25 weeks.

Millipedes feed primarily on decaying organic matter so they are generally not regarded as a pest. However if there are large numbers of millipedes, they may attack roots and leaves of seedling plants. Millipedes, such as the garden millipede, can become a pest in the greenhouse and damage crops with their chewing mouthparts. If a structure becomes infested, then control measures are usually necessary.

In addition, millipedes can excrete an irritating fluid that can irritate eyes, blister the skin or cause allergic reactions to sensitive people so control measures may be needed.

Some Control Options:

Non- Chemical Controls:

Remove areas that provide harborage such as trash piles, rocks, boards, leaf piles, compost piles. If flower beds are mulched against structures, occasionally turn the mulch to allow it to dry out. Check around doors, windows and pipe penetrations for any points of access and then seal any accessible areas that may allow millipedes to crawl indoors.

Chemical Controls:

Perimeter sprays around the foundation of a structure may prevent millipedes from moving indoors. Some products such as those containing deltamethrin, permethrin, bifenthrin or cypermethrin as active ingredients can be used. If treatment inside structures is necessary, all cracks and crevices should be treated. Products such as those containing lambda-cyhalothrin, cypermethrin, permethrin, bifenthrin, or d-limonene can be used.

Photo of a millipede, (Diplopoda). Photo by Bart Drees, Professor and Extension Entomologist, Texas A&M University.

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