WSU Extension Q&A: Everyone says ladybugs are good predators, but I still have aphids in my garden all year. Why is that?

Q. Everyone says ladybugs are such good predators, but I still have aphids in my garden all year. Why is that?

A. Ladybugs are indeed better than the ‘Hungry Caterpillar’. They have been known to eat 30-50 aphids per day. They also survive and reproduce better if there is a variety of pollen sources. In your garden, you may notice a huge outbreak of aphids well before the ladybugs. This is a normal prey-predator cycle. The prey build up in large numbers because the predator population has not yet increased. At some point, the predators become abundant enough that they prey population begins to decline. In aphids and ladybugs, the predatory population can build 2 to 4 weeks after high numbers of aphids (prey). Many of us are not willing to wait that long without some intervention, but rest assured the predator-prey cycles are a natural part of life and will occur.

Q. How is alfalfa hay valued from a dairy perspective?

A. Alfalfa hay is valued in many ways including: protein, energy, fiber, and alfalfa’s quality fiber. Protein only does the dairy cow good if it is metabolized. Alfalfa is about 20 percent crude protein, but only about 55 percent of the crude protein is metabolized.

Metabolized protein is worth 43.8 cents/pound in the Pacific Northwest. Energy concentration of feed fed to lactating dairy cows is calculated and is expressed in Mcalories per pound and currently worth 7.5 cents/pound in the PNW. Fiber is valued at 9.1 cents/pound of neutral detergent fiber. A quality of fiber is based on the Neutral Detergent Fiber content or NDF which if given at rates above 44 percent NDF discounts are applied to alfalfa hay were as if fiber is less than 44 percent then an extra value is placed on the hay. With milk prices are where they are, this discount or extra value is approximately $5 per NDF unit difference from 44 percent. These prices were determined by Alex Tebbe and Dr. Bill Weiss with Ohio State University using a program called Sesame using the prices of feed stuffs in the PNW based on nutrients and their current costs. If you come to the NW Hay Expo on January 17 and 18 you will learn more about this concept. To register visit http://wa-hay.org/.

This story was originally published January 12, 2018 at 2:18 PM with the headline "WSU Extension Q&A: Everyone says ladybugs are good predators, but I still have aphids in my garden all year. Why is that?."