The current screwworm outbreak can likely be contained and pushed back to Panama through sterile fly releases, much like the successful eradication effort of the 1960s. That program remains one of the most effective biological control efforts ever carried out. While today’s infestation differs in several ways, the same approach should still lead to successful control.

One important change since the earlier infestation problem is the availability of more effective anthelmintics and insecticides for treating and perhaps preventing infected animals. In the past, “worm dope” worked mainly by direct contact with the worm and often required repeated applications. Today, treatment is generally closer to a single application followed by careful observation. The greater challenge is finding and identifying infected animals in the first place.

These modern products should be used carefully, because overuse may ultimately cause more long-term damage than the screwworm itself. Excessive mass preventive treatment can drive parasite resistance and leave livestock and wildlife more vulnerable to internal parasites, flies, lice, ticks, and other pests. Over time, parasites can become harder to control, while animals may lose some of their natural genetic resistance to infection-infestation. This risk applies not only to screwworms, but also to many other parasites and insect pests.

Adding feed-grade ivermectin and other very effective products to a wildlife-livestock feeding program may seem like an easy solution. Some argue that wildlife value justifies the cost, but over time this practice could create a net loss for both wildlife and livestock operations.

The time has passed for trying to “kill all the bad guys”—insects, bacteria, nematodes, viruses, and others—at the expense of beneficial organisms. In fact, when studied closely many of the ‘bad guys’ have a place in Natures realm of treasures. (When referring to Nature with a capital N, I am referring to the Lord’s work.) Many grazers have found that routine worming of cattle and sheep, along with treatments for flies, grubs, and lice, is not always needed or even necessary within an effective controlled grazing program. Avoiding unnecessary treatments can improve soil and animal health while helping restore the natural biota that once characterized the New World and its rangelands. Not to mention the cost savings of not applying those added controls, thinking through and applying the ‘whole’ to the ranching program is essential.

Management decisions should be based not only on current conditions, but also on long-term consequences.

THE BETTER IT GETS, THE FASTER IT GETS BETTER

Recently controlled White Brush – Mesquite. Southwest Bristle Grass response has been amazing. Hard to visualize from picture, but livestock and wildlife will have a difficult time getting to it as it is tucked tightly within the dead ‘it is hoped’ white brush. How long it will take for dead white brush to deteriorate is subject to observation.