have made great strides in controlling house flies (pictured here), but mites and dump flies are presenting new challenges.
Alternative layer housing systems, such as enriched cages, cage-free aviaries, and barns with outdoor access, have been designed to provide birds more freedom of movement and to allow the hens to exhibit their full range of natural behaviors.
These alternative systems provide an environment for the hens which is different than what they were exposed to in conventional or battery cages. Enrichments to the bird’s environment, like nesting areas and scratch pads in enriched cages or litter areas in floor or aviary systems, can put birds in contact with feces and provide harborage areas for some pests.
Just as some chicken diseases that had been relegated to old textbooks have re-emerged in alternative housing systems, some old mites have been able to find new homes as the industry has placed more birds in alternative systems.
Mite with a nasty bite
Dr. Jim Arends, president, JAAB of the Carolinas, said that he has seen six or seven cases of grain miller’s mites (Pyemotes ventricosus) in alternative laying systems throughout the past couple of years. He said that in some cases, producers didn’t realize they had mites in the house until the birds had been removed and then the mites start feeding on the workers. The bites cause a very strong histamine reaction in humans.
There is no mistaking whether or not you have been bitten, according to Arends.
“They make a chigger look like a piker,” he said.
The grain miller’s mite is very small -- smaller than the Northern fowl mite.
“They used to be a really common problem in the grain milling business,” Arends said.
These mites are facultative eaters, and Arends said they like grain dust and feathers and can feed on birds and humans as well.
“They don’t need to feed on chickens, but they are just as happy feeding on people or chickens as they are eating feed dust,” Arends said.
We can expect to see the re-emergence of more old pests like the miller’s mite as the industry moves to less restrictive housing and there are new places for pests to hide, according to Arends. Roosts, nesting areas and scratching areas all provide new environments for pests. He said that many of these pests didn’t survive in battery cage environments, but they are coming back in alternative systems. In houses with enriched cages, Arends said he has found grain miller’s mites in the nest area and on the superstructure between the top and bottom of the manure belts and on the underside of the manure belt.
Arends said he has seen one case of red mites (Dermanyssus gallinae) so far in the U.S. Red mites have become a big problem in Europe.
Controlling mites
Getting rid of mites when the flock is removed and the house is cleaned isn’t that big of a problem, but treating birds during the lay period can present some challenges.
“If a flock gets something, it is very difficult to get it out of the house,” Arends said.
Some producers add sulfur to the feed to control mites, but it isn’t effective in all cases. In cage-free situations, egg producers may have to consider going back to dust boxes with sulfur, boric acid or an insecticide dust and let the birds treat themselves, Arends suggested.
Robert Rowland, pest control specialist, IVESCO technical service, said that treating hens for mites in enriched colonies can be particularly difficult. He said that, traditionally, the vent of each bird would be sprayed to kill the mites, but that hens in colonies will bunch up in a corner of the enclosure, making this method unworkable. He said he is working with a producer to devise an alternative method for treating birds in enriched colonies.
Arends stressed that unless a producer has been in the business for 25 or 30 years, they probably haven’t ever seen grain miller’s mites before, so they might not recognize the problem early on. He urged producers to make a phone call for help identifying pests as soon as they suspect a problem.
A different kind of beetle
Egg producers are quite familiar with darkling beetles and the damage they can do to insulation in a layer house, but Arends said that farms that use straw as litter are battling a different kind of beetle. He said he has been to several farms in Canada that use straw for bedding where the hairy fungus beetle (Mycetophagus punctatus) has come into the house on the straw and has become a nuisance. Arends said that the hairy fungus beetle can be even more prolific breeders than darkling beetles.
A predator becomes a pest
The black dump fly (Hydrotaea aenescens) is a shiny black fly similar in appearance to the house fly which is native to warmer regions of the Americas and has been used as a biological control agent on some poultry farms. Black dump fly larvae will kill the larvae of many other fly species, but they are facultative predators and can thrive in manure piles in the absence of other fly larvae to prey upon.
Rowland said that, in the past two years, black dump flies have become a problem in some deep-pit layer houses as well as in some broiler breeder houses. He said that dump flies, like house flies, get a foothold in the house when the adult females find wet spots in the manure piles in which to lay eggs. The dump flies will continue to increase in number even after the house flies are gone, as long as the litter stays wet. Rowland said that on some farms with significant dump fly problems, the presence of the larvae in the manure seems to make the manure “soupy” and, as the infestation spreads, manure removal can become difficult. In some cases, manure can’t be removed with a loader and it has to be pumped out of the house.
In addition to the trouble dump flies can cause on deep-pit layer farms, Rowland said he also has seen dump flies become a problem under the slats in broiler breeder houses. So far, he has seen dump flies become a problem on layer farms in Minnesota, Pennsylvania and Florida.
Dump flies are hard to get rid of once they become a problem in a house, according to Rowland. “You need to go after them as soon as you see them. Once it gets bad, you may have trouble getting the manure out of the house. You would have to pump it out,” he said. Just as in controlling house flies, Rowland said the best preventative measure is keeping the manure dry.
