I can tell it's spring by the number of questions I am getting. Here are my responses to some:

Q: I know we have aphids, but we also have another critter on our plants. It looks like little white specks that don't seem to have any life. Do you know what it is?

A: They probably are aphid mummies. The parasitic wasp, which is a good bug, is causing the mummies. They lay eggs within aphids and then hatch into larva and feed on the inside of the aphids. When they complete their life cycle, they release toxins that cause the aphid to harden and that is what you are seeing. Don't worry about the mummies or you might upset the work of the natural predator.

Q: Just what is insecticidal soap? Can't I just use my own household detergent?

A: While insecticidal soap is chemically similar to household detergents, the active ingredient in insecticidal soap is potassium salt of fatty acids. It controls insects and mites and minimizes plant injury. It also has minimal adverse effects on ladybeetles, green lacewings, pollinating bees and beneficial insects. Liquid dishwashing detergents may increase the risk of plant injury. They are not designed for plant use and will kill the predatory mites, important in controlling spider mites.

Q: What are the white balls of frothy foam on my rosemary plants and how do I get rid of them?

A: It is a spittlebug. The frothy foam is a protective hiding place for nymphs from predators while feeding on plant sap. Forget about them or rinse them off with a strong jet of water.

Q: Last year the vacant lot next door was covered by mustard plants, which later dried up. We found zillions of tiny bugs migrating from those plants. What are they and how can you control them?

A: They are false chinch bugs feeding on London Rocket mustard weed. Once their source of food dries up, they move in hoards elsewhere in search of food. Your best control is to eliminate the mustard and that will eliminate the bugs. Hoe out the weeds or kill them with a dandelion-type herbicide.

Q: Last year a couple of our agaves withered and died from an insect that attacks them at the base of the plant. What can we do to prevent them from killing our agaves this year?

A: You are describing agave weevils. The adults are dusty black weevils.

The adults chew into the base of the agave leaves and introduce a bacterial rot that appears to be necessary for larval development. They lay eggs in the holes and later the larvae burrow into the plant. Later in the summer, the agaves collapse into a rotting mess as a result of the internal infestation and bacterial rot. Remove and destroy infected plants when you find evidence of the damage, along with the larvae and adults from soil around the area. Treat the soil with a grub-type pesticide around the base of all your agaves and yucca plants.

Q: What is causing stippling spots, stunting and leaves a fine webbing?

A: You are describing spider mites. You need a microscope to see them or take a white sheet of paper and place under some branches and vigorously shake them. Immediately move the paper into the light; if you see spots moving, it is mites seeking cover.

They suck sap from leaves, causing yellow spots or stippling as well as twisting and stunting. For large plants (Italian cypress, etc.), direct a strong jet of water weekly for control or use insecticidal soap or a miticide from your nursery.

Q: Is there a good ornamental tree that is adapted to the desert and produces fruit?

A: May I suggest a fig? It makes an excellent ornamental with its large, deeply lobed leaves. With careful pruning you can keep it any size you want, up to 20 feet tall.

Now add in the fig fruit. It will produce two and sometimes three crops a year, the first in June, again sometime in late summer and the third depends on if we get a late frost. But don't look for flowers on your fig tree. Unlike other tree fruits, figs have no exterior blossoms. They develop inside the fruit so you don't need to worry about it being an allergen plant. The varieties for here are Brown Turkey, Black Mission and Green Kadota.

Q: What are aquatic cannas?

A: Jean Womack, owner of Nevada Water Gardens, said they are just like yard cannas but must have wet feet. They are a prime attraction in water gardens. Womack carries Longwood cannas, variegated cannas and red-leafed cannas. The leaves are really attractive.

Q: How and when do I divide cannas?

A: Now is a good time. When you do divide them, plant them soon thereafter and keep the ground moist. Cut them into pieces containing one or more eyes or growing points.

Q: What can I do to attract hummingbirds to my yard?

A: Native flowering plants always attract hummingbirds. The list of favorite hummingbird plants is long. Go to Mountain States Wholesale Nursery www.mswn.com for plants for our valley.

Of course you want to maintain native habitat to encourage hummingbirds to visit your yard. A special hummingbird treat is putting out a peeled banana. The fruit attracts fruit flies, which hummingbirds love. As a side benefit it may attract butterflies.

Hummingbirds prefer water dripping off leaves or sprinklers to bathe in. Try locating misters among leafy bushes. Other birds will enjoy it as much as the hummers.

LEARNING OPPORTUNITIES

First things first: At 2 p.m. Saturday at the Gardens at the Springs Preserve, 3701 Alta Drive, I'll teach you the "how-to" facts of installing your landscape. You'll learn site and soil preparation, grading, drainage, rock selection and construction techniques.

"Let Freedom Ring": At 1 p.m. Saturday, the Nevada Garden Club will present an American flag ceremony in Lorenzi Park, 700 Twin Lakes Drive. Mayor Oscar Goodman and other political dignitaries and garden club members will gather to honor those who serve our country. Across the grounds will be 48 tall American flags representing Nevada soldiers lost in the current war. Other activities are planned for the day. For more information, call 454-1941.

Spring in the Desert: This is the theme of this year's gigantic plant sale sponsored by the Desert Garden Center, which is part of the Community College of Southern Nevada's campus at 6221 W. Charleston Blvd. Expect to find unusual showy plants originating from our valley that you won't be able to get anywhere else. Proceeds from the sale go to enhance the gardening educational classes at the college. There will be speakers to tell you the tricks of gardening in the desert. It will be from 8 a.m. to 2 p.m. Saturday. If you want more information, call 651-5052.

Linn Mills writes a gardening column each Thursday. You can reach him at linn.mills@lvspringspreserve.org or at the Gardens at the Springs Preserve at 822-8325.