Q: I noticed that one of my evergreen trees has a bunch of small brown sacks hanging on it. I thought they were pine cones, but they were soft and hollow when I tried to pick one. What are these things? They are on a part of the tree, which is looking terrible because some of the needles are missing. Do you think this object is the cause?

A: The bagworm, the caterpillar stage of a moth, is eating the leaves off the plants and using some of the leaf parts to make itself a protective covering. This protective bag develops as the caterpillar grows. The bag protects them from insecticides, which should have been applied back in the spring to be most effective. At this time of year, hand-picking them is the most effective and safest control method. On tall plants where you can't reach them all, use a safe product that includes the bacteria Bacillus thuringiensis. The next safest insecticides would be Sevin or Malthion. All insecticides, at this time of year, are going to be less than perfect.

Pretty soon, they will begin the pupal stage, meaning the insecticides will be useless. Then the adult male will hatch and fly around to find the wingless female that remains in her bag. In September, she will lay hundreds of eggs in her bag and then die. From next month until next May, the only effective treatment will be to hand-pick every bag off the plants. Some bags may be empty and some will be old ones from last year, but every female bag will be holding hundreds of eggs.

Q: My zucchini plant was doing fine and giving me a lot of huge fruit, but all of a sudden it died. It only took a day to go from healthy to dead. What can work so fast? How do I prevent it from happening next year?

A: It sounds like your plant had a borer. The squash vine borer is capable of causing a quick death to all kinds of squash and pumpkins. The adult is an unusual and colorful moth, which is about an inch in length with longer wings. The body has a yellow/orange black-dotted or checkerboard pattern. The front wings are black, but the back wings are clear; they are sometimes mistaken for a wasp.

The moths will hatch as adults in June or July — the eggs are kept on the plant. The larvae bore into the vine where they feed for about a month, growing approximately an inch in length. They can feed for a long time without causing much visual damage. Then all of a sudden, they consume enough tissue to stop the flow of water in the vine. Since the vine needs water in warm weather, the whole plant dies very quickly.

The larva then leaves the vine and creates a pupa in the soil. If they started early in the year, like in southern states, they can have two hatchings per year; however, in colder areas the pupa stage occurs over winter and the adults come out the following spring.

Zucchini and Hubbard squash varieties are susceptible to larvae, while butternut squash are less susceptible. Acorn and summer crookneck squash have intermediate sensitivity.

In areas that only produce one set of adults per year, try to plant squash and pumpkins as late as possible — try the end of June instead of April or May.

Q: Something has been eating my tomatoes' leaves. One day the plant looks fine, but the next day whole leaves have been reduced to a stub. I have looked, but I don't see anything.

A: Your tomatoes probably have a green caterpillar, which is hard to see when it is small, but don't worry because it will be big enough to see very soon. It can grow to be about 3 inches long and as big around as your finger. There are two types: tobacco and tomato hornworms, which are easy to tell apart. The tobacco hornworm has white slash marks down its sides that resemble a row of cigarettes. The tomato hornworm contains a row of white V-shaped marks that remind you of V8 tomato juice. Both caterpillar types have a prominent horn on the tail end of the body, but it is colored red on the tobacco hornworm.

The caterpillars often remain vertical against a tomato or pepper plant stem during the day and then feed in the evening. They move from plant to plant, if the plants are close enough to reach. Being such a big caterpillar makes them a fine meal for birds; therefore, they don't want to move around often when they can be seen. The fresh ones are moist looking, but by the next day they have dried and become much smaller. Look under the plants for the large new ones in order to locate the area where the caterpillar has moved. They also leave behind large pea-sized droppings.

The caterpillars are susceptible to being parasitized by a tiny wasp. If you find a caterpillar with white bumps or egg-like structures sticking out of its body, leave it alone. The wasp larvae are feeding inside the caterpillar; they will hatch out of the white bumps, creating a natural control measure.

The adults of these caterpillars are large moths that can be as big as 3 or 4 inches across. They have a row of large pink or orange square dots bordered in black on both sides of its body. Called hawk or sphinx moths, they often hover in front of flowers and are mistaken for hummingbirds.

E-mail questions to Jeff Rugg, Kendall County unit educator, University of Illinois Extension at jrugg@uiuc.edu. To find out more about Jeff Rugg and read features by other Creators Syndicate writers and cartoonists, visit the Creators Syndicate website at www.creators.com.

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