Tree insects

Each year in late spring and early summer, homeowners begin noticing strange growths on the leaves or stems and are concerned for the health of their trees. Several different types of galls are common on Nebraska trees, caused by the feeding or egg laying activities of insects or mites. Either the physical damage done by the insect or its salivary secretions as it feeds causes the plant to increase its production of plant hormones. These plant hormones cause abnormally increased plant growth in small, localized areas and result in the formation of a gall.

If you have a saucer or star magnolia in your landscape, magnolia scale is a troublesome insect. At this time of year, they make their presence known by causing sap to rain down beneath infested trees. Anything below, like patio furniture or cars, gets a sticky coating. An integrated approach is necessary for control, targeting the most vulnerable life stages at specific times of year.

Dropping soon onto a patio near you – let me introduce the ash sawfly. Or maybe you’ve already been introduced to this insect; your Nebraska Extension office has been getting questions about this little greenish “songbird Snickers bar” all week!

Here’s the bottomline, this is ash sawfly and it isn’t going to kill your tree. Interested in a few more details?

If your landscape has a history of bagworm problems, it’s time to start looking for the next generation of young insects. They will soon be hatching.

The insects and their cocoons can be hard for gardeners to spot since they look so much like a natural part of the plant. Many people don’t realize the pointed oval structures the insects create and carry around with them aren’t a natural part of the tree. Last year’s bags are easier to spot than the tiny structures made by new insects.

Every summer an unusual type of insect makes an appearance in many landscapes. Actually, there is a small group of insects, called twig girdlers or twig pruners, that cause similar damage in a variety of trees. But fortunately, these insects are not a serious problem and their activity doesn't have serious consequences for the trees. But their presence can be seen as small twigs at branch tips turn brown and die.

Sawflies are a common pest found on evergreen trees in spring and they can seriously damage conifer trees through defoliation. Several species of sawflies are present in Nebraska, including the European pine sawfly (image above), yellowheaded spruce sawfly (image below left) and larch sawfly (image below right). The European pine sawfly (EPS), Neodiprion sertifer, was accidentally introduced and first found in North America in 1925 in New Jersey.

"What is this webby mass in my River Birch and is it going to kill the branches? My neighbor told me I should prune it all out of my tree and burn the branches." This is a common question received by Nebraska Extension in late summer and fall.