Spotted Lanternflies Love Height and Heat

Dead spotted lanternfly at the base of a utility pole, 13 Sept 2023 (photo by Kate St. John)

13 September 2023

They aren’t very smart but they know what they like: warmth and vertical objects.

If you haven’t been to Downtown or Oakland lately you’re missing an insect phenomenon. Our plague of spotted lanternflies (Lycorma delicatula) is quite attracted to tall buildings and utility poles, especially when it’s hot.

Spotted lanternflies love this utility pole when the sun heats it (photo by Kate St. John)

Like moths to a flame, spotted lanternflies are visually drawn toward and seemingly captivated by vertical objects such as utility poles …

[They] turn and land on the poles when they are less than about 10 feet away. They remain on the pole for many minutes, even hours, while crawling up toward the top to try to take flight again.

However, a large proportion of those launching themselves from the pole are drawn back to the pole, which serves as a sort of “visual magnet” from which the insects cannot escape for a while. 

Science Daily: Lanternfly’s attraction to vertical silhouettes could help monitor, trap it, April 2021

On hot days I see thousands above me, puttering toward the buildings, tapping along the structures as they try to find a place to land.

This building is especially attractive to spotted lanternflies, Sept 2023 (photo by Kate St. John)

The bugs cling and fall off, leaving drifts of lanternfly carcasses on the ground below.

Spotted lanternflies litter the base of the Rand Building, 11 Sept 2023 (photo by Kate St. John)

There’s a theory that the bugs like vertical objects because they are such weak fliers that they have to climb up and relaunch on their search for their host tree, the Tree of Heaven (Ailanthus altissima). According to Penn State Extension, they “land on buildings for warmth, height and other unknown reasons.” Other unknown reasons: Who can know the mind of a lanternfly?

Fortunately we can learn from Philadelphia where their spotted lanternfly plague hit in 2020 (during the pandemic). Here’s what happened at a taco shop on the ground floor of a high rise.

video from NBC10, Philadelphia, Sept 2020


Note that Philadelphia had their lanternfly plague in 2020 and now, three years later, they are wondering where all the bugs have gone. I’m sure we can expect 2-3 summers of this nonsense. Certainly by 2026 spotted lanternflies will just be a bad memory in Pittsburgh.

(credits are in the captions)

3 thoughts on “Spotted Lanternflies Love Height and Heat

  1. The new building at Craig Street and Centre Ave. seems to be Laternfly central – every time I go by it I make sure ALL the windows are shut tight! And I saw my first egg mass the other day, on a tree at Western PA School for the Deaf. Unfortunately it’s inside the fence so we couldn’t get to them.

Leave a Reply

Your email address will not be published. Required fields are marked *