Missouri Master Naturalists- Springfield Plateau Chapter

Tuesday, November 1, 2022

Red Velvet Mites

Our WOLF School field trip last week included hiking down the old Mail Trace Road looking for little things in the woods.  Almost every student found one or more of these small things crawling slowly in the leaf litter, red velvet mites ( RVM). They are also called "rain bugs" because they come out after a rain like we had earlier. 

Mites are arachnids as are spiders, harvestmen, scorpions and the ever popular ticks.  Like ticks they have six legs in the first instar, then graduate to eight legs from then on into adulthood.  RVMs are members of the Trombididiidae family of mites which gives us several thousand species to choose from.  

You can see "velvet" close up.

Their lifecycle is complicated, beginning as eggs and then several inactive pre-larval stages.  The final larvae are parasites on insects and spiders (but not us mammals!)  The adults feed on the insects or their eggs, then mate and produce eggs for the next generation.

RVM are not chiggers and it is hard to find good reputable photographs of real chigger mites. There are several species with the blood-sucking habit, the most common being Trombicula alfreddugesi.  Their larva sticks its proboscis into our skin and injects digestive juice which hardens into a tube called a stylosome, the source of the itching inflammation as described here by Missouri University.

Wikipedia
Chigger mites on the other hand are tiny, requiring a magnifier to see them.  I doubt if anyone reading this has ever seen the mite.  Only the 6 legged larval stage is parasitic, feeding on reptiles and birds. The MDC Field Guide tries to reassure us that "mammals (including people) are secondary, almost accidental hosts."

"Their presence is best known, instead, by the intensely itchy welts they leave behind, usually where your skin is thin and tender (ankles, backs of knees, about the crotch, under the beltline, and in the armpits) and where tight clothing proves an obstacle to them (as where a belt or elastic band limits their wanderings).  Chigger bites sometimes have a tiny red dot at the center, which is the remains of a scablike tube your body formed in response to the chigger's irritating saliva."

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The Bug Lady has in depth information on RVMs and their interesting mating habits at this link.