Q: What is the best insecticide to treat an in-ground nest of yellow jackets? Mary Floyd, north Atlanta

A: Any insecticide dust would work well. Locate the hole during the day then drop no more than 2 tablespoons of the dust into the entrance at dusk, when they have all returned to their nest. A dust works well because each insect has to walk over it as they exit the nest. The 2-tablespoon limit is just a reminder that there’s no need to dump a whole bag into the nest. A little dust around the entrance is all that’s needed.

Q: A friend sent me the ingredients a mosquito control company is pushing for organic mosquito control. They include rosemary oil, clove oil, cedar oil and peppermint oil. They seem harmless enough, which makes me think the treatment is ineffective. Your opinion? Marian Gordin, Decatur

A: Some, but not all, essential oils like these have been shown to repel mosquitoes. I found research supporting the use of citronellal, alpha-pinene, and limonene, but my search was not exhaustive. Sometimes, the combination of different essential oils works better than any one by itself. They are not required to be proven to be effective. Essential oils are allowed to be sold for mosquito control because they are generally regarded as safe to humans. In your friend’s case, I guess the proof is in the pudding. If she sees fewer mosquitoes, the company can be deemed to have done its job. In any case, her lawn will smell better than all of her neighbors’!

Q: I have a fescue lawn and it’s taken a beating with the dry, hot weather. It looks a bit dull and there are a few weeds creeping in. Should I fertilize? Ken Pruitt, email

A: Fertilizer isn’t the answer. With daytime temperatures in the 80s and 90s, it’s just too hot for fescue to grow well. Nights are not cool enough for fescue to recover from daytime heat. I think you could apply Ironite now to make the grass green with soluble iron. Irrigate to avoid wilting, but only to supplement natural rainfall, not to exceed 1 inch of water per week.

Q: Each of my four hummingbird feeders holds 60 ounces of food. I see lots of birds feeding all day and the feeders must be refilled every three days. I live in the country and have only one large butterfly bush in my landscape. People are amazed at the number of birds. Can you explain why? Earl Saunders, email

A: As my mother would say when remarking on another’s success: “It must come from good clean living!” Congratulations!

Email Walter at georgiagardener@yahoo.com. Listen to his occasional garden comments on “Green and Growing with Ashley Frasca” Saturday mornings on 95.5 WSB. Visit his website, www.walterreeves.com, or join his Facebook Page at bit.ly/georgiagardener, for his latest tips.