Extension Communications
3614 Administrative Services Building
Ames, Iowa 50011-3614
(515) 294-9915
6/25/01
Contacts:
Donald Lewis, Extension Entomology, (515) 294-1101,
drlewis@iastate.edu
Elaine Edwards, Continuing Education and Communication
Services, (515) 294-5168, eedwards@iastate.edu
Yard and Garden Column for the Week Beginning June 29
Do Your Trees Bug You?
By Donald R. Lewis
Extension Entomologist
Iowa State University Extension
Our shade trees provide many benefits around the home, including natural cooling, increased property values, improved aesthetics and so forth. Of course, there are a few downsides to owning trees, but the disadvantages such as fallen leaves, dropped twigs and occasional pruning are generally tolerable.
But what about bugs from trees? There are a few trees that are infamous for periodically producing lots of bugs. The boxelder bug, for example, is a well-known, autumn-time household accidental invader that spends the summer months on maples, boxelders and other trees and the winter in nearby attics and walls. As near as we can tell, the liquid sap sucked from stems and seeds is insignificant to the trees. The annoyance to homeowners, however, can be severe! The good news is that the insects that spend a portion of their life cycle away from the trees and in our personal space are harmless. They don’t bite, sting or carry diseases and they do not feed on fabrics, furniture or the house structure. They are pests simply by the annoyance of their presence.
This occasional annoyance of insects from trees does not mean we should avoid all trees, or even eliminate certain species of trees from our landscape. Trees are just too valuable to discard on a whim, and a temporary, buggy inconvenience does not justify removal of an otherwise valuable asset on your property. Evaluate carefully any over-simplified advice claiming that tree removal will solve your bug problems. Remember there are no simple answers to life’s complex questions!
Sycamore seed bug
The sycamore seed bug, one of the least familiar of the bugs from trees, is making one of its rare appearances in Iowa this summer. The common name of this small, tan insect tells most of the story. It is a bug, found only on sycamore trees (Platanus occidentalis) where it feeds on the seeds.
Sycamores are large trees recognized by their large, stiff, three-lobed leaves and the creamy white exfoliating bark on the branches and upper trunk. Sycamores often reach 100 feet tall and are one of our tallest native deciduous trees.
Sycamore seedpods are golf ball-size, brown balls that hang individually on a long tough stem. The seed pods (technically known as fruits) form in mid to late summer, ripen in the fall and then persist well into the winter and even into the following summer. My neighborhood sycamore tree still has hundreds if not thousands of seed balls still hanging on the tree refusing to fall. Each pod contains hundreds of tiny seeds attached to a small piece of tan fluff. Seeds are released as the pods break apart on the tree or after the pods fall to the ground and are run over by the lawn mower. Sycamore seeds travel in the wind like dandelion seeds and accumulate in "drifts" in corners and crevices.
This abundance of persistent seedpods on the sycamore trees probably explains why there are more sycamore seed bugs this year. Sycamore seed bugs have elongate bodies pointed at both ends and up to 1/4 inch in length. The color is dull yellow to light reddish-brown. The seed bugs can be found nestled into the pods but are more commonly noticed crawling on the sunny side of your white-sided house. It is not clear why the bugs leave the trees and their food to wander across vast expanses of house siding. One theory is that the seed bugs have been dislodged by recent storms and rain and are trying to travel back to the tree. Of course, they have no sense of direction so they ramble aimlessly (or more commonly, back and forth in one area).
We know very little about the sycamore seed bugs but can determine most of their habits from recent observations. They apparently spend the winter in the adult stage and lay eggs in old seedpods during the spring. Nymphs are present in late May and June. Another one or two generations will probably occur in mid to late summer.
A final, interesting observation of sycamore seed bugs is how they smell. When crushed they have a distinctive, moderately unpleasant, pungent odor. If you grind a sycamore seedpod between your fingers it releases the same odor, proving once again, and even for bugs, you are what you eat.
Sycamore seed bugs are not harmful to trees. Obviously sycamores have way too many seeds, and any decrease in seed populations would be a welcome relief! The wandering bugs might be annoying on the house siding, windowsills or patio, but can be safely ignored. Wash them off with soapy water if you need something to do, but otherwise wait for them to disappear.
ml: isugarden
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