Not too many things are more annoying in the summer than trying to work and getting bothered by flies. Seeing calves, water and feed buckets covered with flies, or evidence of their presence, is nasty.
Fly control may seem an untimely topic when I drove through rain, snow, and sleet on the way to work this morning. However, decisions made now can impact fly numbers this summer.
Now’s the time. Numerous sites around dairy farms provide potential breeding habitats for flies: manure, spilled feed, high moisture locations, bedded packs in calf hutches or pens.
One study in Maryland found maggot counts ranging from 50 to 70 housefly and 12 to 20 stable fly maggots per quart of bedding material from calf hutches (that was per quart, not per hutch). Pity the technician who had that job!
Estimated populations of 25,000 to 40,000 adult flies per hutch per summer were possible.
Where to start. How can we decrease or eliminate populations? Reducing attractive sites to lay eggs and grow maggots is most important.
Site hutches on well drained locations. Grading the site and adding stone for a solid base is an important long-term investment.
Keep starter grain in the grain buckets. Is the calf spilling grain out of an undersized bucket? Is the calf feeder actually getting all of the grain in the bucket, or feeding it in the vicinity of the bucket? Clean up spilled grain accumulations.
Clean house. Keep starter grain in the buckets clean. If water, milk, urine or feces get into the starter bucket (and it is truly incredible how many calf feeders under 16 can’t see it if it does,) a hefty crop of fly larvae will be growing in the bucket of feed. Calves are not going to eat this mess.
Collect old water and dispose of it away from the hutches rather than dumping out buckets near the hutch where they can contribute to fly population growth.
Check the bedding. Bedding type is a major factor in the buildup of fly populations. For cold weather, deep, loose straw is the gold standard for providing calves with a place to nestle down and preserve body heat. In summer, it is the gold standard for fly production.
Over several years, hutches at the USDA Beltsville Research Station were bedded with either straw, pine shavings, sawdust, sand or gravel during the summer months. Not surprisingly, nearly zero maggots were found in sand or gravel, the inorganic bedding materials. However, they found them difficult to manage, losing drainage through the packs and generating foul odors.
Quality and grade of sand and gravel will make a difference in how well they might actually work. Some sands have too much dirt in them and will quickly pack into a hard, poorly drained surface.
What worked. Sawdust was the best organic performer, reducing house and stable fly maggot populations by 77 percent to 81 percent compared with populations in the straw-bedded hutches.
Straw bedding supported stable fly populations ranging from 64 to 81 maggots per quart of bedding. Pine shavings were used for one summer and reduced house fly maggot populations by 57 percent, but supported the same population of stable fly larvae as the straw packs.
Changing bedding materials for the summer can help reduce fly populations associated with calf housing.
Clean, well-drained and ventilated grounds and facilities will always be important. Selecting a summer bedding material that is maggot-unfriendly and managing for calf cleanliness and comfort is another good strategy.