A “Fluffy” Surprise Found Among the Leaves of a Hackberry Tree

Authors
Curtis E. Young
Joe Boggs
Published on
Leaves of a common hackberry tree covered with black sooty mold.

Curtis Young in NW Ohio (Lima, Ohio) came across a common hackberry tree (Celtis occidentalis) with leaves covered in sooty mold. The sooty mold was dense enough to darken the upper surface which caught his attention from a short distance away from the tree. Upon closer inspection by rolling the leaves over, there were two prominent insects present on the underside of many of the leaves, mulberry whitefly (Tetraleurodes mori) and a woolly aphid. The whitefly was easily identified for it infests numerous species of plants. On the other hand, the woolly aphid was a new and unfamiliar insect to Curtis on hackberry.

 

Common hackberry tree with leaves darkened by sooty mold growth.
Common hackberry tree with leaves darkened by sooty mold growth.

 

 

Common hackberry tree leaf infested by mulberry whitefly and woolly aphids.
Common hackberry tree leaf infested by mulberry whitefly (black oval-shaped objects surrounded by a white fringe, pupae of the whitefly) and woolly aphids (young nymphs (“naked” light-green aphids) to winged adults (the largest white fluff balls)).

 

 

A heavy mulberry whitefly infestation on the underside of a hackberry leaf.
Mulberry whitefly infestations can be heavy on individual leaves. The above image shows numerous whitefly pupae and newly emerged whitefly adults scattered between the pupae.

 

 

Numerous winged adults and newly birthed nymphs on the underside of a common hackberry leaf indicating a transition from one generation to the next.
At the time of discovery (8-1-2024), the population was transitioning from one generation to another with numerous new adults and numerous newly birthed nymphs on the same leaves.

 

A quick search on the internet did turn up several fact sheets and references to a woolly aphid on hackberry and sugarberry (C. laevigata). Sugarberry is not native to Ohio, but common hackberry is very common and easily found in NW Ohio.

 

An old fence line populated by numerous volunteer common hackberry trees.
Old fence line where nearly every tree that grew up along the fence is a common hackberry tree.

 

The aphid was identified as the Asian Wooly or Woolly Hackberry Aphid (Shivaphis celti).

 

A close-up view of an adult Asian Woolly Hackberry Aphid.
A close-up image of a winged adult Asian woolly hackberry aphid. Wax threads or filaments are secreted through the exoskeleton producing the white fluffy appearance of the woolly aphid. Even the antennae and legs are covered in fluff.

 

As its common name implies, it is native to Asia and was accidently introduced into the Eastern United States. It was first discovered in Georgia in 1996. It has spread into most of the southern states and up the eastern coast to at least Maryland. It has also spread or potentially been separately introduced into California where it was first discovered in 2002. Now the woolly aphid is found throughout California.

 

In a conversation with Joe Boggs, he relayed that in recent years, he has gotten calls from residents in the Cincinnati area with complaints of little balls of fluff floating in the air and heavy loads of sticky stuff covering objects below large hackberry trees. Joe confirmed that it was the Asian wooly hackberry aphid in Ohio. Apparently, it has made it to northern Ohio as well.

 

Two winged adult Asian woolly hackberry aphids covered with white waxy filaments.
When these fluff-covered adults take to flight, they look like floating snowflakes or cotton candy. The fluffy wax filaments made focusing on the insects difficult.

 

 

An Asian woolly hackberry aphid with its waxy fluff removed to show its physical characteristics.
An Asian woolly hackberry aphid adult stripped of its waxy filaments to reveal some of its physical characteristics used in identification such as the banded coloration of the antennae and dark coloration over the veins of the wings.

 

The tree that was and is infested is in a metropark where it and several other trees were planted in the landscape. Other nearby hackberry trees have varying levels of aphid infestation. Looking closely at the leaves and taking pictures of the leaves revealed a wide range of ages of the aphid from newly birthed to winged adults indicating that the population is still growing. An inspection of other hackberry trees at other sites had no evidence of infestation, but may become infested in the future.

 

Since this aphid appears to be a relatively new aphid in Ohio, Joe and Curtis are curious as to how widespread it may be in Ohio. So, they would like to get reports from anyone that is currently experiencing the presence of this woolly aphid on their hackberry trees. Send them a note at either young.2@osu.edu or boggs.47@osu.edu. Thanks in advance to anyone who responds to this request.

 

 

 

 

 

Tags
Common Hackberry Tree
Sooty Mold
Asian Woolly Hackberry Aphid
Mulberry Whitefly