Tip information provided by Jim Appleby, entomologist, Natural Resources and Environmental Sciences, University of Illinois, Urbana-Champaign

When hundreds of nymphs are feeding at the same time the plant will become weakened. The plant's foliage may turn pale, and the new growth may be greatly stunted. If the soil becomes dry the plant will wilt much sooner than normal.

After completing their nymphal stages which lasts about three weeks, the mealybugs will become adults. If the are males, they will emerge from very small white cottony-like cocoons as small winged insects. The males will fly to the females and mate with them and then die. The adult wingless females continue to increase in size and begin to produce large amounts of waxy, cotton-like substance around their bodies. Within the cottony masses are produced the numerous eggs. When all the eggs are produced the female dies. All stages of the mealybugs may be present on a plant at any time. If uncontrolled the mealybugs will eventually kill the plant.

During the nymphs' feeding they will excrete sugary clear fluid called honeydew. The honeydew will fall onto leaves and other objects beneath their feeding sites. The leaves at first will become very shiny and feel very sticky. Then a black sooty fungus will start to grow on the honeydew. The leaves now appear to have a black or grayish-black film. Because of the amount of light available to the leaves is greatly reduced due to the sooty fungus, the affected leaves are not able to function normally and will die.

For control, first try to remove as many of the large female mealybugs as possible. This can be accomplished with a cotton swab that is used to crush the insects. Then thoroughly spray the entire plant with an insecticidal soap. The soap treatment must be repeated at weekly intervals until a total of four (4) treatments have been made. The repeated applications are absolutely necessary because the soap treatment will not kill any undetected adult female mealybugs or any of the eggs. Soap will only kill the younger nymphs, but eventually with repeated spraying, all of the nymphs will be killed. Be sure to follow all instructions on the soap label.

During the months of April and May, red, mugo, Scotch, and Austrian pines are often attacked by the larvae of the European pine sawfly. The larvae are very gregarious, and will almost always feed in groups. The larvae feed only on the old needles; the new needles produced during the spring months are never fed upon.

The mature larvae are about an inch in length with shiny black heads, the rest of the body is gray-green with black longitudinal stripes. With the least disturbance, the larvae often will twitch in unison. This behavior is probably a defensive maneuver to ward off predators and parasites. All the larvae twitching together may appear as one large animal rather than individual larvae.

If the larvae are abundant in many areas of a true, their feeding may cause complete defoliation of the of needles. Such defoliation will not kill the tree, however the tree is weakened. The following year the new growth may be stunted. Trees devoid of their old needles have a poor appearance.

Control Methods

If a sawfly infestation is very light with only a few trees affected and only a few branches infested, then a cultural control can be used. Pour some hot soapy water into a pail. Hold the pail beneath the infested branch and flick the larvae into the solution. When an infestation is heavy, an insecticide spray may need to be applied. Acephate (Orthene), malathion, or carbaryl (Sevin) applied as a spray will control the larvae. There is no need to spray the entire tree, apply the spray only onto the larvae. Bacillus thuringiensis will not control sawfly larvae. Sawflies are related to ants and wasps and B. thuringiensis is effective only in controlling moth and butterfly larvae.