ORLAND PARK, IL—For the third uneventful day in a row, members of the Poison Ninjas Club awaited the invasion of their tree house, sources in the backyard of 1740 Sumac Road reported Monday.

Willliams and friends wait for someone to invade their tree house.

"We spent all day Saturday making dirt bombs and dragging buckets of pine cones up into the tree house," said 10-year-old club president Carrie Williams, her eyes trained on the southern border of the lawn. "When the enemy attacks, we'll be ready. Actually, we've been ready for, like, three whole days."

After standing guard throughout the weekend, Williams and her fellow Poison Ninjas left the tree unsupervised while they attended school on Monday. The Ninjas reconvened at the tree house after school and found their supplies undisturbed and no evidence of nefarious activity near the tree. Disappointed, they took up arms once again and began to stare out at the lawn in search of some sign of a threat.

"We have the Super Soaker loaded and ready to go," 10-year-old Jason Alvin said, referring to a large squirt-gun that he has emptied into the air around the tree house several dozen times. "If they don't get the message from the water gun, we'll let them have it with the balloons. Except we have to go and fill up more water balloons, because most of them broke in the pail overnight."

The tree house is an eight-square-foot wooden platform situated in the branches of an 80-year-old oak tree in the Williams' backyard.

"Absolutely no one is allowed in the tree house unless you're a member of our club," Williams said. "We have a password and everything. It's 'Valencia.'"

Williams' father built the structure in August 2001 for Williams' older brother Kurt, who ceded it to her earlier this summer.

"Dad said he's going to replace the old wooden ladder with a rope ladder, so we can pull it up after we climb up," Williams said. "That way, when they're looking for a way up, we can whale on them with the crab apples. Well, the ones we didn't already throw on the roof of the neighbors' house."

"No, we should pee on them," Williams' 7-year-old brother Josh said, eliciting a howl of disgust from the assembled club members.

One corner of the tree house contains a coverless cooler stocked with five cans of Sprite, a package of beef jerky, and a bag of Twizzlers.

"We had some Halloween candy up here, but we ate it," Williams said. "Now, we have a rule that we can't eat the rations, in case we get surrounded and have to live off them."

Although the Ninjas couldn't say who exactly the enemy was, the candidates included a group of classmates referred to as "The Cootie Sisters," several older boys from the neighborhood who allegedly covet the fort as a haven for smoking cigarettes, and an eighth-grade couple whose motives were unknown. Additional threats cited by the children include bullies, mean dogs, and kidnappers.

In spite of the disparity between the number of armaments in the tree house and the number of actual attackers, the Ninjas continued to explore defense options.

"I thought it would be cool to have a secret escape tunnel," 9-year-old Ninja treasurer Willie Braniff said. "But you'd have to dig out the center of the tree, and that would kill it. Plus, the tunnel would come out in Mrs. Kellington's yard, and she would probably yell at us."

Other adults have hampered the children's efforts to man the tree house.

"Mom won't let us spend the night up there, because we might roll out and break our necks," Williams said. "We thought we could maybe put [the family's Schnauzer] Muffin up there as a watchdog at night, but she kept slipping out of the rope harness."

As an alternative, Williams has kept a silent watch from her bedroom window each night, to ensure that the tree house is secure.

"I told everyone that if I see anyone near the tree house, I'll call their houses and hang up the phone," Williams said. "Same thing goes for when everyone has to eat dinner."

There has been a high attrition rate among sentinels, with the club losing four members since the perceived conflict began. The first left Sunday, complaining of outdoor allergies. Roll call Monday after dinner heralded the loss of two more guards, one to a soccer game and another to a visiting aunt. One member was forced out due to his negligence.

"We told Jay [Conroy] that if he kept playing his Game Boy instead of watching the hole in the fence for cats, we'd kick him out," Williams said. "He didn't argue with us at all. He just got up and left."

It wasn't until Conroy was out of throwing range that one of the remaining Ninjas thought of testing Ninja defenses on the deserter and yelled "Fire!"

"It's been a long couple of days for the ones of us left behind," Williams said. "I don't know how much longer the others can keep this up. Winter is coming soon. As for me, I'm not going anywhere until I get a chance to empty this giant garbage bag full of leaves on somebody's head. The waiting will make that Sprite taste all the sweeter."