Released: August 15, 2005

Know the Bug By the Bite

MANHATTAN, Kan. – One of the challenges of being a “bug person” at Kansas State University is fielding the phone calls that ring in each summer from annoyed, uncomfortable people who want to know: “What bit me?”

“Because of the itch mite outbreaks Midwesterners experienced last year, we’ve been getting numerous calls, reporting incidences of such bites again this year,” said Alberto Broce, K-State Research and Extension entomologist. “Most often, however, the descriptions we’ve been hearing do not match those that are typical of itch mite bites.”

The fact is, all kinds of flying, hopping and creepy-crawly creatures emerge in spring and summer, hungry for blood or other human-related food, Broce said. Although they leave irritating reminders of their success, many have mouthparts designed to cause little pain. They can steal a meal, almost unnoticed.

For example, mosquitoes, ticks, biting lice and fleas take the hypodermic needle approach, inserting a thin “tube” through the skin and into a blood vessel. In contrast, horse flies, black flies and stable flies take the scissors or axe approach, slashing through skin and lapping or sipping the blood that flows out, he said.

To help people assess the “reminders” that pests leave behind, Broce developed the following criteria for identifying three of the more common types of bite: itch mite, chigger and mosquito:

Itch Mite - About 10 to 16 hours after being under or near oak trees (mainly pin, red and black oaks), the victim develops symptoms. At each bite site is a rosy-red swollen area about one-fourth inch wide with a fluid-swollen vesicle or pimple in the center of the welt. The bite is in a place that was bare or covered by loose-fitting clothes – for example, on neck, chest, face or arms.

The bite causes intense itching, and scratching can lead to a secondary bacterial infection. Unlike with chigger and mosquito bites, however, scratching itch mite bites is painful. Even uninfected bites persist for about two weeks.

“The bites are a reaction to the itch mites’ saliva. It contains a potent neurotoxin,” Broce said.

Chigger - Victims mostly develop itchy chigger bite sites after walking through grassy or weedy areas, particularly in shade or part shade. Chiggers’ preferred dining sites are “tight” places – under the belt, bra and/or socks and in the skin folds of the crotch, knees and/or armpits.

How soon the itching starts depends on how long the chigger needs to jump on for a ride, find a good bite site (usually in a hair follicle or pore), and then secrete the saliva that digests human skin cells for it to eat. Generally, everything but the final step takes less than 15 minutes.

“The itching may or may not lead to painful scratching. Two of the deciding factors are how quickly you bathe and whether you apply a sealant-antihistamine combination,” Broce said. “Unchecked, chiggers can continue injecting saliva and eating dissolved skin for 3 to 5 days.

“You’ll still be able to tell whether a chigger or itch mite caused the bite, however, if you look at the bite’s placement on your body and remember if you’ve been around grass, rather than oak trees.”

Mosquito - Mosquito bites can vary greatly from person to person. Typically, they’re swollen, reddened areas. Often they have a vesicle with fluid. Humans’ reaction to mosquitoes’ feeding can develop in a matter of minutes or be delayed.

Mosquitoes can bite through light clothing. Like mites, however, they usually attack where skin is exposed.

“You’ll know your attacker wasn’t an itch mite, however, if you don’t have to wait hours and hours for a reaction. You’ll know it wasn’t a chigger because of where the bite is located on your body,” Broce said. “Besides, mosquitoes are most likely to be active in early morning and evening, and that sometimes is the best clue that a mosquito was at fault.”

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K-State Research and Extension is a short name for the Kansas State University Agricultural Experiment Station and Cooperative Extension Service, a program designed to generate and distribute useful knowledge for the well-being of Kansans. Supported by county, state, federal and private funds, the program has county Extension offices, experiment fields, area Extension offices and regional research centers statewide. Its headquarters is on the K-State campus, Manhattan.

Story by:
Kathleen Ward
kward@oznet.ksu.edu
K-State Research& Extension News