Pine Tortoise Scale

Louis F. Wilson ¹

The pine tortoise scale (Toumeyella numismaticum (Pettit & McDaniel)) is a soft scale insect that periodically kills hard pines. It is a native insect and was first reported in eastern Nebraska in 1911 and later officially described in 1920 from specimens obtained in northern Wisconsin . It was probably carried into Nebraska from Wisconsin on infested, wild jack pine seedlings used to estab­lish an experimental planting in 1891.

The currently known range is from eastern New York south to Maryland and west through the North Central States to the Great Plains wherever its hosts are found. It is also known to occur in Manitoba and Ontario, Canada.

The taxonomy of the genus Numismaticum is still undecided, and it is possible that some reports of T. pini King actually refer to the pine tortoise scale.

Some collections of T. pini from Pennsylvania, Maryland, and West Virginia are now considered to be at least a form near T. numismaticum.

Hosts
Trees of all sizes are attacked. Preferred hosts are Scotch and jack pines. Austrian pine (P. nigra var. austriaca A. & C.) also is commonly attacked, but red pine is attacked only when it is growing adjacent to or mixed with the preferred hosts. The form of Toumeyella considered to be near numismaticum attacks Virginia pine.

Damage and Evidence of Attack
Heaviest damage occurs on seedlings and young saplings, al-though pole-sized trees are some-times severely injured. Feeding of the nymphs and adult females on the twigs causes branches to die (flagging). Heavily attacked trees turn yellow and finally die. In most heavily infested jack pine stands, a few trees escape attack completely, apparently because of an inherited immunity.

Associated with this scale is a sooty mold that grows on honeydew—a secretion given off by the immature female scales. Together, the honeydew and the black mold (fig. 1) on the needles give the tree a shiny dark appearance. Ants often feed on the honeydew.

Figure 1.-Heavy attacks cause a sooty mold on the foliage. (Courtesy Ohio Agricultural Experiment Station.)

Description
The eggs are ovoid, pinkish, almost transparent, and about 1/64 inch long. To the naked eye they appear collectively as a fine pow-der beneath the female scale.

The first-instar nymphs—called crawlers—are nearly as large as the eggs and oval and have six short legs. They are reddish, and to the naked eye they appear as"fine red pepper" sprinkled on the twigs.

The older nymphs are legless, helmet-shaped insects. The female nymphs are larger than the males and often wrinkled and dark brown to black. When mature, the females (fig. 2) are 3/16 to 1/4 inch long and reddish brown. The most obvious evidence of the presence of male scales is the puparia. These are oval, white, and trans-lucent and about 1/8 inch long (fig. 2). The adult males, which are seldom seen, are winged and barely 1/6 inch long.

Figure 2.-The pine tortoise scale and predators: A, mature female scales; B, puparia; C, ladybird beetle predators. ( Courtesy University of Wisconsin )

Life History and Habits
There is one generation per year. The female scale produces about 500 eggs, which are laid and develop under the female in June and early July. The crawlers hatch within a few hours, crawl out from under the female, and disperse. Many walk to new areas on the same host, but others are carried to new hosts by wind. Some may be carried to new local­ities on the feet of birds.

The crawlers settle down and suck the sap of the host and shortly afterward become seden­tary, legless nymphs. A white, powdery substance develops on the margins of the young nymphs, and in about 2 weeks sexual differentiation becomes apparent. About 1 week later the smaller, male nymphs are fully developed. They pupate and emerge as small, flylike adults. They immediately search out and fertilize the still immature, immobile, female nymphs and then soon die.

The fertilized females continue to develop until late fall, when they hibernate (fig. 3). They resume activity in the spring about the time the buds begin to swell. Honeydew is secreted copiously during this time and is accompanied by the sooty mold and ants. The females mature in early June.

Figure 3.—Immature, hibernating female scales. (Courtesy Ohio Agricultural Experiment Station.)

Natural Control
Because this scale is often con-trolled by natural agents, the forest owner should examine his trees to determine the abundance of these agents before resorting to the use of insecticides. Several species of ladybird beetles, both as larvae and adults (fig. 2C), attack the young scales and the eggs under the mature female scales. Heavy scale infestations have been almost completely de­stroyed by these predators. Hy­peraspis congressis Watson, pre­viously considered as binotata (Say), is by far the most abun­dant species. Also reported as exerting a strong controlling ef­fect in various parts of the scale's range are Hyperaspis signata (Oliv.), Chilocorus bivulnerus Muls., Scymnuslacustris Lec., Coccinella transversoguttata Fald., C. trifasciata L., C. novem­notata Hbst., and the chalcid parasite, Microterus fuscicornis (Howard). The larvae of the pyralid moth Laetilia coccidivora (Comst.) noticeably reduced scale populations in Ohio in the late 1930's and in Maryland, West Virginia, and Pennsylvania in 1957.

Chemical Control
Malathion can be used to con­trol the crawlers in late June and early July. An effective aerial spray consists of 1½ pints of 57-percent malathion emulsifiable concentrate in 2 gallons of water, applied at the rate of 2 gallons per acre.

Because malathion has a short period of effectiveness, crawlers that have become sedentary—about 1 week after hatching—will not be affected by the chemical. Consequently, spraying should be done twice—first within 4 to 5 days after the first hatching and again 5 or 6 days later.

Pesticide Precautions
Pesticides used improperly can be injurious to man, animals, and plants. Follow the directions and heed all precautions on the labels.

Store pesticides in original con­tainers under lock and key—out of the reach of children and ani­mals—and away from food and feed.

Apply pesticides so that they do not endanger humans, livestock, crops, beneficial insects, fish, and wildlife. Do not apply pesticides when there is danger of drift, when honey bees or other pollinat­ing insects are visiting plants, or when they may contaminate water or leave illegal residues.

Avoid prolonged inhalation of pesticide sprays or dusts; wear protective clothing and equipment if specified on the container.

If your hands become contami­nated with a pesticide, do not eat or drink until you have washed.

In case a pesticide is swallowed or gets in the eyes, follow the first aid treatment given on the label and get prompt medical attention. If a pesticide is spilled on your skin or clothing, remove clothing immediately and wash skin thoroughly.

Do not clean spray equipment or dump excess spray material near ponds, streams, or wells. Because it is difficult to remove all traces of herbicidesfrom equip­ment, do not use the same equip­ment for insecticides or fungicides that you use for herbicides.

Dispose of empty pesticide containers promptly. Have them buried at a sanitary land-fill dump, or crush and bury them in a level, isolated place.

WARNING: Recommendations for use of pesticides are reviewed regularly. The registrations on all suggested uses of pesticides in this publication were in effect at press time. Check with your county agricultural agent, State agricul­tural experiment station, or local forester to determine if these recommendations are still current.

References

A NEW MENACE TO SCOTCH AND JACK PINE. J. H. ALLISON and L. W. ORR. Jour. Forest . 27:821-824. 1929.

CONTROL OF TOUMEYELLA SCALE ON VIRGINIA PINE.  A. T. Drooz. Jour. Econ. Entomol. 50:835. 1957.

THE PINE TORTOISE SCALE (lecanium numismaticum PETTIT AND MCD.) IN NEBRASKA.  L. M. GATES. Jour. Econ. Entomol. 23:544-547. 1930.

THE PINE TORTOISE SCALE IN WISCONSIN.  P. A. JONES and R. D. SHENEFELT. Univ. Wis. Res. Note 30, 3 p. 1956.

NATURAL FACTORS CONTROL THE PINE TORTOISE SCALE IN THE NORTHEAST. THOMAS MCINTYRE. Jour. Econ. Entomol. 53 :325. 1960.

SOME ASPECTS OF THE BIOLOGY AND DISPERSAL OF THE PINE TORTOISE SCALE (toumeyella numismaticum PETTIT AND MCDANIEL) (HOMOPTERA: COC­CIDAE). F. B. RABIIN and R. R. LE‑ JEUNE. Canad. Entomol. 86:570-575, illus. 1954.

TWO NEW SPECIES OF THE GENUS HYPERASPIS (COLEOPTERA: COCCINELLIDAE). W. Y. WATSON. Canad. Entomol. 92:230-234, illus. 1960.

Use Pesticides Safely

Follow the Label

U.S. Department of Agriculture

U.S. Government Printing Office: 1971 O---409--975