When Josh Tarr started his freshman year at the University of Maryland a few weeks ago, his younger sister found herself without a chauffeur and back on the school bus. And, suddenly, there was no one around to tease her in the cafeteria.

“It’s been weird,” Kayla Tarr, 15, said of life at home in Louisiana since her big brother left. “A lot of times my brother would annoy me, but now I kind of miss him annoying me.”

So much energy goes into ensuring that freshmen smoothly transition to college life and that moms and dads can cope with the separation. Meanwhile, younger brothers and sisters are often forgotten.

Some colleges now offer sibling programs during student orientation, but the focus is usually on recruiting future students, not discussing how life at home is going to change. Although “parents weekend” has become “family weekend” at many schools, much of the attention is still directed at those writing tuition checks.

Even a quick family discussion can help younger siblings understand their emotional ups and downs are normal, several psychologists said. Some children genuinely miss older siblings, even if they have trouble admitting it. But many middle kids savor being on top of the sibling stack, even if only until Thanksgiving break. And the youngest kids rejoice at not having to compete for mirror time in the bathroom, keys to the car or total control of the television remote.

Up to this point, many of these siblings had to live in the shadows as parental energy was focused on college applications, campus visits, senior prom, graduation, shopping for dorm stuff and preparing for the big move.

“Suddenly, the big dog is gone,” said Marshall Duke, a psychology professor at Emory University. “It’s not a bad thing. It’s like pruning a flower garden. ... You trim back a bush, and the flowers behind it can now blossom.”

Rachel Israel moved from Fairfax County to McDaniel College in Maryland this year, giving her younger brother Jacob a quieter house and his parents’ undivided attention. A sophomore at West Springfield High School, he plays the clarinet in the marching band and is sometimes too busy to call his sister.

“It seems like he’s finding his own niche,” said Rachel Israel, 18, a freshman studying history. “There’s just so much going on in his life that I don’t know about.”

Israel said she will often talk to her mom before calling her brother so she can get the full scoop and not repeat questions he has already answered for his parents.

“He gets frustrated when too many people ask him the same questions,” she said.

Jacob Israel, 15, said he looks forward to talking with his sister.

“Like with any sibling, they aren’t always going to be missed 100 percent,” he said. “But it’s close.”

All of that parental attention can quickly annoy, he said: “If your parents care about your school grades, they will be all over you.”

The same is true in the Tarr household in Louisiana, where Kayla is now the only child and her mom often wants to talk and talk and talk. Meanwhile, Sherri Tarr said she worries about her daughter getting lonely without 19-year-old Josh around.

“She’s gotten so quiet,” the mother said. “Sometimes I can tell she wants me to give her some space. ... It’s hard because she’s the only one I can give my attention to.”

There are some things middle and high school students would rather discuss with an older sibling than mom or dad — like algebra shortcuts, crushes and teachers who uphold pointless rules. Under the same roof, it’s easy to ask. From a distance, it’s harder.

“It takes a lot more preparation,” said Michael Monaco, 18, a freshman at the College of William and Mary. He chats a few times a week with his sister, Mary, a seventh-grader, through online video. “It’s almost like I’m talking to a friend.”

The two discuss homework, things they have written and their favorite online game, Minecraft. Sometimes Mary worries that she’s bothering him too much, “but it’s just nice to see his face again,” she said.

As younger siblings flourish in a less crowded house, those who are at college can feel left out. Although parents don’t change much in a semester, siblings can grow several inches, change personalities and pick up new habits.

Tasha Wemhoner, a freshman at McDaniel, misses her two older siblings and two younger brothers in Colorado. She also has two step-brothers in Iowa.

“It’s always loud and crazy in my house,” said Wemhoner, 17, the first in her family to attend a four-year college. “At first it was kind of nice to be away because things were so calm.”

She keeps in touch through Skype, text message, e-mail and Facebook, but it’s not the same as sharing a bedroom with her older sister. Or walking her youngest brother home from elementary school.

“He would always tell me what he had for lunch that day,” she said. “I’m kind of sad I’m not seeing his first grade year.”

Wemhoner will fly home in mid-December for winter break. Since she arrived in Maryland in August, she knows she has changed and assumes her siblings have as well.

“It’s going to be really different when I get back,” she said. “So much has changed in two months. I can’t imagine how much will change in five months.”