Mites in Mealworm Bin

In doing my research on starting a mealworm colony, I noted that grain mites can be a problem.  To avoid this catastrophe I dutifully microwaved the bedding substrate.  No problems.  When my last batch of mealworms ordered suffered an inordinately high rate of die off, to include the pupae which had about a 33% mortality rate, I increased the moisture.  My mealworms were fantastically happy.  However, this past weekend, seemingly overnight, I had a mite infestation.

In checking on my mealworms, I noted  webby stuff in a coffee filter basket (which I used for the water crystals.  When I looked closer, I realized that the bins were covered with fine white, moving mites.  Clearly, this was not a minor battle, but those little buggers (spiders actually) were in full siege mode.  They were crawling EVERWHERE.  And even though I had taken precautions and had separate bins, all of them were contaminated.  (Now I realized why I felt crawly things on my arms a few times last week after checking on mealworms.)  When I checked my wheat bran bag, (in the garage and far way from the colony, that was contaminated.  So clearly microwaving (or microwaving the way I did it) was not 100% effective.  However, I also introduced some brewer's yeast + I increased the humidity level quite a bit + I had some vegetable matter, so the source of the infestation could be manifold

I wasn't about to throw it all out.  Too much painstaking work went in to raising this first batch of worms which were now at feeding size for my bird customers.  Plus, I need to get pupae to replenish my 1st generation beetles who are running out of steam.  Here's how I'm choosing to handle--and I'll update on results.

• took all bins outside.  I had a bin with incubating eggs worms and a large bin with more mature worms.  Beetles are still doing their thing.
• sifted worms out but could not sift out all bedding.
• Cleaned the containers with soap water and then a final rinse of bleach (and final rinse)
• Put the worms (and their contaminated bedding into one of the bins).  
• Began a process of  creating an isolated colony of mite-innoculated worms.  
• I picked out individual worms in the contminated bin (but still less so) and gave them a wash off. That sounds crazy, but it worked. I simply put the worms in a fine sieve strainer, immersed it in water, and then rinsed under tap.  I then put them on a paper towel.  They did not appear uncomfortable, and they are thriving and happy.  None have died.  I was gentle, but they likely felt briefly water-boarded.

 I'm continuing to let the mite-infested colony exist with periodic harvesting for feeding the birds as well a a 'wash up' to increase the non-invested colony for development to pupae. For the mite-infested colony, I have deployed these strategies:

• Put a band of vaseline around the top boarder of the bin to keep the mites from migrating out.(I found this helpful hint on the web)  (PS:  this does not work well)
• Wiping down the sides of the bin with a vinegar soaked sponge to capture and destroy the hundreds and hundreds of little moving white dots. 
• keeping the humidity level lower.

Though not an insignificant amount of works, my customers love it.  While waiting for my mealworms (1st generation) to mature to eating size, my customers went away.  That was fine as there were no nestlings/fledglings at the time.  Now that I'm back in the feeding business, the Carolina Wrens are feeding fledglings, and I have some Bluebird juveniles (3) that are coming to the feeder with a female.  I'm wondering if they are from the last fledge from the nest box.  And, my Summer Tanager girl has come back.  I have missed her.  Though, the bluebirds (even the juveniles) are very inhospitable.