Try to ignore bulbs, bulging during spring on aspen trees

I have several bulbs/bulges on my aspen trees branches this spring. I have cut through one, and it looks like an insect is embedded inside. Do you know what they might be? What can be done?

— Travis

You’re asking a question many people do this time of year. People are getting out in the yard cleaning up and “re-acquainting” themselves with the garden and notice these strange rounded swellings on the twigs of their aspen.

They’ve actually been there for about a year, but we notice them now because they’re not hidden by the leaves of the tree.

What you have is a little insect called the poplar twiggall fly. The adult stage of the insect looks like a tiny miniature housefly. The female has a sharp stinger-like structure (don’t worry, they don’t sting) that cuts a slit in the bark where she deposits an egg or two. She also secretes a chemical that causes that rounded swelling of the twig that we call a gall.

The enclosed egg hatches and during the larval stage spends the spring and summer munching on the soft pulpy center of the gall. It spends the winter as a pupa and emerges the next spring to start the cycle all over again.

Though these galls may look a little alarming, they very rarely damage the tree. The insect is only inside for the first year, but the gall will usually continue to grow for several years along with the branch.

Eventually, the gall stops and is “swallowed up” and reabsorbed by the branch as it continues to grow.

There really is no spray for you to use on these guys. Trying to kill the very mobile female fly before she lays eggs is almost impossible. There’s a bit of research about using systemics to kill the larva, but we’ve had hit or miss results with it. Besides, you may kill the larva inside but the gall is already there and will continue to grow.

The best way to approach it is to consider it an aesthetic problem and try to ignore it. Besides, those leaves will soon be out to hide them.

I have a giant sacaton grass that I want to move. I thought it was OK to move in spring, but I just read fall is best to move grass. Can I still do it in the spring if I do it very early?

— Laura

I think the best time to transplant is early spring, usually sometime in March.

You want to do it while the plant is still dormant but right before it’s due to wake up and start growing so it can settle into its new home and heal the damage transplanting has done.


When is the best time to plant a fruit tree in this area? Does it matter if it is in a pot or not?

— Lacie

If the trees are growing in pots, you can plant them just about any time you’d like. There’s very little stress on the plant since you’re not “messing” with the roots very much.

In the Grand Valley, we’ll usually plant up until the first or the middle of December. When the ground freezes, we stop. It’s not that it is a bad time of the year to plant, it’s just too much work to dig a hole when things are frozen.

Bare root plants should be planted in the spring as early as you can work the ground, getting them in as early as possible so they have a chance to begin rooting back out and re-establishing themselves before the hot weather hits.

Dennis Hill is the nursery manager at Bookcliff Gardens, Send questions to Bookcliff Gardens, 755 26 Road, Grand Junction 81506; or email .(JavaScript must be enabled to view this email address).


Commenting is not available in this channel entry.

Search More Jobs

734 S. Seventh St.
Grand Junction, CO 81501
970-242-5050; M-F 8:00 - 5:00
Subscribe to print edition
Advertiser Tearsheet

© 2015 Grand Junction Media, Inc.
By using this site you agree to the Visitor Agreement and the Privacy Policy