Keep Calves More Comfortable with Fly Control Measures
by Kelly Driver
The temperatures are warming up and it is time to think
about ways to manage the fly population around our calf facilities. Flies are
the major pest problem for dairy calves and are more than just a nuisance as
they can also spread diseases like E. Coli and Salmonella. Flies can
also keep calves from resting comfortably, causing them stress and reducing
growth rates. And I would be remiss if I didn’t mention that flies present the
same challenges to the calf care team. So, let’s talk about some measures than
can help create a healthy, stress-free calf zone for all parties.
Identify the pests. Knowing the types of flies that you are dealing
with as well as their lifecycle is the first key in developing an effective fly
management plan. Stable flies, house flies, and blow flies, all commonly
classified as “filth flies”, are the most common types found around dairies.
They are labeled “filth flies” because they prefer moist conditions and like to
lay their eggs in manure, decaying organic matter, spilled or spoiled
feedstuffs, and damp bedding, according to Dairy Herd Management. Other
common flies that are more often found in pastures or open areas can include
horse flies, deer flies, face flies, horn flies, and even mosquitoes. Several
of these pests are biting flies that require a “blood meal” and can be quite
disturbing to calves. Sarah Morrison, researcher at W.H. Miner Institute, Chazy,
NY, notes that stable flies cause painful bites on the lower legs of calves,
damaging their tender skin, even to the point of causing noticeable hair loss
and scab formation. (Hanson) House flies are the most prevalent in numbers and
while they don’t bite, they are effective carriers of disease. The Cornell
University College of Veterinary Medicine notes that the house fly’s life cycle
is a quick 10 days, while stable flies complete their life cycle in 3 to 4
weeks. (Bertoldo)
Control Options. While it may feel like fly season is
still weeks away, it is much more effective to start fly control measures
before flies appear. It is important to develop an integrated pest management
plan (IPM) to maximize fly control efforts at your operation. IPM focuses on
three key areas: sanitation, biological control, and chemical control. (Hanson)
Take the time now to walk around your farm facilities, identifying any fly
breeding areas and where maggots might live, then determine how to make these areas
less attractive to flies.
Keep it clean. Both house and stable flies breed in
manure, decaying silage, and moist bedding or feedstuffs, making sanitation the
key management practice. Since the house fly life cycle is just 10 days,
cleaning everything possible weekly is most desirable and removing any spilled
or leftover feeds daily is also helpful. Spreading manure in a thin layer to
promote quick drying can also help. (Bertoldo)
Another important sanitation measure is keeping the bedding
in the calf housing area dry. Some farms switch to sand, wood shavings or
sawdust as bedding material instead of straw in the warmer months of the year.
Opening rear doors and vents on Calf-Tel hutches or pens to encourage airflow
will also help keep the bedding dry.
Biological control. Releasing natural predators in
the spring months can help keep fly populations from blooming. Parasitic wasps,
Muscidifurax raptor, will selectively lay their eggs in the larvae of
house and stable flies and effectively prevent it from developing. This is the
only species of wasp that is effective against the house fly, according to
Cornell University’s College of Veterinary Medicine, and should be released on
a weekly basis from mid-May through August in northern states. (Bertoldo) Additionally
there are beetles and mites that are also predatory to flies, but “these
insects are also subject to the same chemical control effects as the flies,
meaning that residual insecticides and larvicides cannot be used in conjunction
with parasitic wasp releases”, notes Dr. Gerald Bertoldo, DVM with Cornell’s
Pro-Dairy team.
Another option is an insect growth regulator, which is a
feed additive that can be added to milk or milk replacer beginning several
weeks before the start of fly season. Implementing a feed-through larvicide
before flies’ hatch works by disrupting the development of the fly’s
exoskeleton in immature flies, killing them so they do not become adult flies.
(Dairy Herd Management) This break in the life cycle results in fewer flies
buzzing around later and does not require extra time or labor to implement. If
these products are part of your IPM, be sure to read the label and feed them
until 30 days after cold weather arrives for best results.
Chemical control. At times judicious use of short
acting chemical methods may be needed to supplement fly control measures. Long
acting residual products can provide an immediate effective knockdown, but a
resistance can develop to them. Space sprays and baits are effective and less
apt to promote resistance. (Bertoldo) Items like fly bait traps, pour-on
insecticides, fly bait poisons and sticky tapes can also work well as part of
an integrated pest management plan.
An added perk. An effective fly control program
creates a much more pleasant environment for both the calves and the people
caring for them.
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Kelly Driver has been involved in the New York dairy
industry all her life. In addition to raising dairy calves and replacement
heifers, she is the Northeast Territory Manager for Calf-Tel. Feel free to
contact her at kellydriver@hampelcorp.com with your
calf questions or suggest a topic you would like covered in a future blog.
Sources:
Bertoldo, Jerry, DVM. (Internet). Bedding, bugs and calves:
maintaining comfort and health. Retrieved from https://www.vet.cornell.edu/animal-health-diagnostic-center/programs/nyschap/modules-documents/housing-bedding-fly-control
Dairy Herd Management. (Internet). Fly control strategies
for dairy calves and heifers. Retrieved from https://www.dairyherd.com/article/fly-control-strategies-dairy-calves-and-heifers
Dairy Herd Management. (Internet). Fly population management
on dairies. Retrieved from https://www.dairyherd.com/article/fly-population-management-dairies
Hanson, Maureen. (Internet). Protect your calves during fly
season. Retrieved from https://www.dairyherd.com/article/protect-your-calves-during-fly-season?mkt_tok=eyJpIjoiT0RJME1qWTROV0ZsTkRBNSIsInQiOiJcL2RaOWs4YmFNMExRSXRaY0lseWRGbkFkTXVjSkw0M1RJOXRPXC84WVhjYzZTN2pTbStmdk81MkdMRV
Loftin, Kelly M. & R. Corder. (Internet). Fly Control
for Organic Dairies. Retrieved from https://www.uaex.edu/publications/PDF/FSA-7072.pdf
Purina Animal Nutrition. (Internet). How to get a head-start on fly control. Retrieved from https://www.purinamills.com/dairy-feed/education/detail/how-to-get-a-head-start-on-fly-control