The ‘dweller’ dung beetle Sphaeridium scarabaeoides, a predator of fly larvae observed 4/21/17 in Tionesta, PA.
In my interactions with livestock graziers I learned about beetles that you can find in the manure patties. Last week I found some on a farm in Leola, Lancaster County and on a farm in Forest County. They just started activities on the northern farm. These lowly animals prove to be a lot more important than you'd think - and our livestock and pasture management affects how well they will do.
There are three types of dung beetles: rollers, tunnelers, and dwellers. The rollers are the most famous - you have probably seen them in some documentary taking care of elephant dung in the Kenyan savannah. However, we also have rollers in Pennsylvania. Rollers create a ball from the manure and subsequently roll it to a place where they bury it in the soil. Tunnelers dig into the manure and then take little balls into tunnels they dig under the manure patty. Finally, there are dwellers, which just live and lay eggs in the manure patty itself.
Dung beetles are between 1/8" - 1¼" long depending on species and are typically brown or black and one species is metallic green. Roller and tunneler dung beetles lay one egg in each manure ball they put into the soil. The egg hatches in 1-2 days into a larva. These larva are 'C' shaped grubs that go through several instars. After 1-4 weeks the larva pupates. Adult beetles will emerge 2 weeks to several months later, depending on species and environmental conditions. Dung beetles can play a very important role on your farm, if populations are large enough.
- They can help reduce problems with face and horn flies - livestock pests that also propagate in manure. The primary mechanism of fly control is by competition for manure - the dung beetles remove fresh manure from the soil surface. However, there are also dung beetles whose larvae may feed on fly larvae in the manure pat. We found Sphaeridium scarabaeoides dung beetles (a 'dweller' type) in Tionesta that are known to be predators of fly larvae.
- They recycle nutrients and incorporate manure into the soil. Dung beetles have been known to take care of a manure pat in 24 hours!
- They can increase forage production because manure does not cover the vegetation and cows graze the entire field (they typically don't graze around manure pats).
- The tunnelers and rollers make soil more porous and incorporate organic matter into the soil, thus improving soil porosity and biological activity. The larvae typically consume 50% of the manure ball, while the rest is left.
There are many different species of dung beetles. In a study in North Carolina, 14-28 species were observed in different pastures. The beetles were observed from spring to fall.
Insecticides and dewormers such as abamectin, ivermectin, eprinomectin, and doramectin kill flies and dung beetles in manure. High stock density grazing favors dung beetles by supplying many manure pats in a small area for easy colonization. Dung beetles are also helped when you come back to a pasture when adult dung beetles emerge. Dung beetles can fly quite a distance - up to 30 miles. They locate manure using smell. So they can populate a crop field that is being grazed if there are dung beetles in the area. This could help to improve soil health in continuous no-till fields that are being grazed.