Blowfly Risk and How to Reduce It

The blowfly season is lengthening, with an earlier emergence of flies, largely due to the changing climate.  For this reason, producers should be very cautious of fly strike occurring earlier than normal.  This article outlines how to reduce flystrike through reducing breeding sites, and how to prevent it.

For fly eggs to be laid, a temperature of 9-10^oC and rainfall or humidity is required e.g. a dirty backside.  As the season progresses the fly population increases.  The majority of flystrike is caused by the green bottle, who will lay ~200 eggs at a time.  The eggs will remain on the host, only for a short period of time, in which time they will lay in the wool, hatch and crawl to the animal’s skin.  After 12 hours the eggs hatch, provided there is the humidity to do so.  The larvae then feed for 3 days, before crawling away from the site, dropping off the sheep and pupating in the soil.  When a sheep has multiple infestations e.g. numerous flies laying eggs, then a wound is created, and the odour is attractive to other flies.

Managing Blowfly

To avoid flies being attracted to your animals and reduce the availability of breeding sites, there are three management steps that can taken,

1) Ensure deadstock is lifted promptly, prior to uplift store in a sealed box

2) Minimise potential egg laying sites

• • dagg and crutch dirty bums
  • implement Worming Strategies etc.
  • shearing
  • tail docking
  • treat any wounds quickly e.g. horn falling off, tups fighting, etc

3) Management of Footrot

Control of fly strike requires good management, in combination with preventative products.  Baited fly traps are a good tool, to monitor blowfly activity, and assist with timing of product application.