The weather warms. The eggs hatch. The creatures stir.
They crawl up the trunks of oak trees to dine, and millions of dollars worth of Maryland hardwood starts to die.
Bob Tichenor has the job of controlling the voracious leaf-eaters, which fatally weaken trees by defoliating them.
It's man against gypsy moth.
The annual struggle is set to begin. Thousands of state residents already have received letters alerting them to the coming bombing runs on bugs, by helicopters and fixed-wing aircraft flying 50 feet above the treetops.
As chief of the state's forest pest management section, Mr. Tichenor uses scientific forecasting and aerial spraying to suppress a moth population that last year defoliated 93,147 acres of woodland, more than 95 percent of it on the Eastern Shore.
Insect reinforcements could appear at some point -- immigrant Asian moths with more mobility and appetite. But the garden-variety gypsy, which began attacking Maryland forests 14 years ago, remains Mr. Tichenor's chief concern.
Not long after the newborn moths appear as caterpillars next month, he will start sending out aircraft loaded with chemicals.
The state has targeted 67,000 acres of woodland for spraying, more than half of it on the Shore. Every county there will have some woodlands treated, but most of the acreage is in Caroline, Wicomico, Worcester and Talbot counties.
For the second straight year, Central Maryland probably will escape widespread infestation, but the spray plan lists 18,000 acres there -- including portions of Baltimore, Carroll and Howard counties -- and 12,000 acres in Southern Maryland.
Last spring, heavy spraying in Western Maryland prevented defoliation, and Mr. Tichenor hopes the same strategy on the Shore will foil his adversary.
"This is one robust, complex little bug," he says. "We're not here to wipe out [gypsy moths], but to intervene. It's not practical or biologically sensible to have horizon-to-horizon spraying, when the moth probably would survive anyway."
Maryland's infestation began in 1981, as the forest pest moved into Harford and Cecil counties from Pennsylvania. (Imported to Massachusetts from Europe as a silkworm, the gypsy got free in 1869 and headed south.)
Feeling at home in Maryland, the bugs toured the western part of the state, tarried in the Baltimore-Washington corridor and seem to have settled east of the Chesapeake Bay, where many oaks also reside.
Egg masses laid the previous year begin hatching in April, each mass releasing hundreds of caterpillars. Some start munching leaves immediately; others are carried by wind onto trees as far as a mile away.
Unique markings -- five pairs of blue dots, followed by six pairs of red -- make the crawlers easy to distinguish, says Mr. Tichenor. "These are not the caterpillars that make tents in your cherry trees, or the ones that eat cabbages in the garden."
Defoliation continues until June, when the caterpillars become adult moths. The brown-winged males, which can fly, seek out the whitish females, which cannot. After mating, the female lays her eggs on a tree, woodpile or other sheltered location, and the adult moths die.
Their natural enemies include birds, white-footed mice and parasitic wasps and flies. But Mr. Tichenor says those feeders have little effect in heavily infested areas, where the gypsy multiplies so quickly that "predators can eat themselves silly without denting the population."
Last year the moths defoliated 5 percent of Maryland's 1.75 million acres of hardwood forest.
Defoliation is not the immediate cause of a tree's demise but often is the death sentence. A year or two of severe leaf loss limits the tree's ability to nourish itself and leaves it vulnerable to disease, other insects and drought.
That's a tragedy, says Mr. Tichenor, because trees are so critical to the ecosystem. "They anchor the soil, clean the air, cool the earth and cover wildlife."
Last year Maryland lost about $14 million worth of hardwood because of gypsy moths, says Donald VanHassent of the state Forest Service. Moreover, removal of a large dead oak from a suburban yard can cost the owner more than $1,000.
Oaks are majestic, slow-growing trees that provide good shade and strong wood. Gypsy moths are partial to them but will feast on other trees, including birch, apple, willow and pine. "I've been in wooded areas of Kent County where virtually the only things growing were tulip poplars and rhododendrons," Mr. Tichenor says. "The moths even ate the nonwoody plants on the forest floor."
In 1994, Maryland's control program cost $2.1 million; the total since 1981 is nearly $25 million.
Mr. Tichenor, 43, has moth-busting credentials. A native of New Jersey, he has a biology degree from Bucknell University and a master's degree in entomology from the University of Delaware.
His department spends much of its time trying to anticipate the moths' movements. With help from the cities and counties, the state monitors about 25,000 locations to develop forecasts of likely infestations for a coming year. But as with weather predictions, the system does not work for the long term because the gypsy, true to its name, is a wanderer.
Mr. Tichenor points to a map showing the gypsy's relentless, 126-year march from New England across the continent. Moving at a snail's pace of 12 miles a year, the moths most recently invaded Ohio and Virginia. "They're just now entering the heartland of the Appalachians, which are filled with oaks," he says. "These insects won't stop until they reach Mexico."
Meanwhile, state officials are watching for signs of the Asian species of gypsy moth -- larger, hungrier and more active than its kin.
Asian moths have been found in seaports in North Carolina, Oregon and Washington. They attack a wider variety of trees than gypsies and spread more rapidly: Females can fly up to 20 miles.
The good news? When Asians first arrive and begin to mate, their fearsome traits get lost in the vast gene pool of the resident population.
"It's possible the Asian gypsy moths are already here but of no consequence, because they've been overwhelmed by native moths," says Mr. Tichenor. "The danger is when [Asians] find a lightly infested area and can dominate the gene pool."
But that is unlikely in Maryland, because of the large number of gypsy moths already in the state.
D8 "It's the only time I'm glad they're here," he says.
13 COUNTIES HIT
A state survey shows that in 1994, gypsy moths defoliated 93,147 acres of woodlands in these 13 counties, eight of them on the Eastern Shore:
Dorchester ......... 23,324
Worcester .......... 17,466
Wicomico ........... 16,431
Caroline ........... 10,955
Queen Anne's ........ 9,074
Somerset ............ 5,110
Talbot .............. 4,754
Prince George's ..... 2,422
Kent ....... ........ 1,921
Charles ............. 1,388
Montgomery ............ 159
Frederick ............. 132
Anne Arundel ........... 11