Get ready for chigger season
Wednesday, May 22, 2013 1:00 AM
Chigger season is approaching, so now is a good time to learn more about these pests and what to do if you run into them (literally).
Chiggers, or redbugs as they are sometimes called in the South, are not actually insects, but are tiny red mites in the family Trombiculidae.
These mites have 4 life stages: egg, larva, nymph, and adult.
While small mammals, birds, reptiles, and amphibians are the normal hosts for the parasitic 6-legged larval stage, humans can serve as "accidental hosts" if they encounter the larvae.
The 8-legged nymphs and adults feed on small insects or organic matter and do not affect humans.
The larvae are present from spring to late fall, but are most active in the summer.
They do not bite if the ambient temperature is below 60 or above 99 degrees.
Chiggers live in moist, low-lying areas with abundant vegetation.
These same areas attract springtails and small insects on which the nymphs and adults feed.
The female mites emerge in the spring and lay their eggs in small groups.
The larvae emerge within a week and seek suitable hosts nearby.
On humans, they seek moist or thin-skinned areas such as wrinkles at the knees or underarms.
They also tend to bite at constrictions in clothing, such as sock cuffs or waistbands.
Chiggers do not feed on blood, but instead eat liquids released from skin cells of their hosts.
As they bite the hosts at skin pores or hair follicles, they release a tissue-dissolving enzyme and then suck up the protein-rich fluids from the stylostome, or deep hole that forms in the skin.
The cells lining the stylostome harden, no longer releasing liquids, and the chiggers drop off the host in 1 to 2 days.
The larvae then develop into nymphs, followed by adults that overwinter in the soil.
In warmer climates, several generations can develop in a year. In humans, intense itching begins 1 to 3 hours after receiving chigger bites, which appear as flat or raised red areas on the skin.
Contrary to popular belief, the itching is not caused by mites that remain under the skin, but by the digestive enzymes that are injected by the chiggers.
Scratching the bites because of the itching, which is most pronounced during the first 2 days, may introduce secondary infections, but otherwise the skin lesions should disappear within 2 weeks.
Secondary infections are treated with antibiotics.
No prolonged effects result from chigger bites in the U.S., but in areas of Southeast Asia and Australia a number of mites transmit scrub typhus, a potentially severe rickettsial disease that can involve the central nervous system in 6-13 percent of patients.
If you are exposed to chiggers, take a long, hot shower or bath using plenty of soap and wash your clothes as soon as possible.
To relieve the itching, use corticosteroid creams, calomine lotion, or oral antihistamines.
Over-the-counter products such as Chiggerex (active ingredient benzocaine 5 percent) can be very effective at controlling the urge to scratch the bites.
Take preventive measures if you will be entering habitat preferred by chiggers.
Apply insecticide containing DEET to pant legs, collars, and shirt cuffs.
Wear boots, and tuck pant legs into your socks or tape or tie pant bottoms tight to prevent the chiggers from crawling up your legs.
Occasionally brush your clothing or skin to knock off any chiggers that may have climbed aboard but not latched on.
Avoid shady areas.
Controlling the vegetation in the area can also knock down chigger populations. Keep lawns mowed or cut paths through natural grassy areas and clear brush to avoid contact with the plants the chiggers rest on, waiting for hosts to pass by.
Identify chigger hot spots by standing a black card up vertically on the ground and observing the number of tiny orange larvae that crawl to the top edge of the card (keep in mind that some may be other mites), or by dragging a white sheet baited with dry ice across the ground (chiggers are attracted to carbon dioxide).
To learn even more about insects through the 4-H Entomology project, give me a call.
My phone number is (601) 656-4602.
May 27 - County 4-H Office Closed for Memorial Day.
May 29-31 - 4-H Club Congress, MSU.
Until next week, get into 4-H!