Tag Archives: invasive

Houdini fly alert for owners of bee hotels

If you have an insect hotel, you should check your mason bee nests for Houdini flies (Cacoxenus indagator) before the season starts. These non-native flies consume the pollen inside mason bee nests, causing the bee larvae to starve to death. They are very easy to get rid if have nesting tubes that can be taken apart.

Killing them at the larval stage is easy. Just unwrap your nesting tubes during the winter and squish the larvae (below) before they mature into adults. If you’re not into squishing things, submerge them in alcohol or soapy water before discarding.

Houdini fly larvae

I had a half-dozen or so cells infested with the flies, so killing them removed approximately 100 individuals (below) from my local population. That won’t eliminate them from my yard but at least my hotel is not part of the problem.

Houdini fly larvae

Here are photographs of the adult. They look like common fruit flies but are darker and considerably less skittish when you approach them — they are so chill you can often squish them with a finger (do that if you can). You’ll notice them lurking around a bee hotel waiting for female mason bees to leave their nesting tube unguarded, then they’ll slip inside and leave a load of eggs.

If you find Houdini flies at your hotel, please upload a photograph to iNaturalist so we can track their spread.

Below are mason bee cocoons, for comparison. You can clean off the frass and mud, wash them, then store outside in a way that protects them from birds and moisture. For details on all how to do that, see this page. If you store them in an unheated garage in a container, check them at least every day so that you can release them.

Mason bee pupae

Photograph of cryptic spotted lanternfly egg masses

The river birches at the Morris Arboretum in Chestnut Hill, PA, were loaded hundreds or perhaps thousands of spotted lanternfly egg masses, all of them amazingly camouflaged. Can you find them on the trunk below? Click on the photograph to view a larger version.

Cryptic spotted lanternfly egg masses on river birch

In addition to trees, spotted lanternflies can oviposit on a variety of artificial surfaces such as shipping containers, cars, trains, and garden tools. Their fondness for hard, smooth surfaces means that humans unwittingly transport them across state lines.

Here are the locations of the egg masses.

Cryptic spotted lanternfly egg masses on river birch

More photographs of spotted lanternflies are on my SmugMug account. Please also see my post, “Spotted lanternfly control tips“, for details on how to kill eggs, nymphs, and adults.

Spotted lanternfly photographs

I’ve posted a few pics of the invasive spotted lanternfly (Lycorma delicatula) on Instagram but thought I’d feature my full collection in a post. The insect is extremely photogenic but it’s also good to let people know what different stages look like so that everyone can kill them. I still need some early-instar pics as well as some showing spotted lanternflies being consumed by parasites and fungi.

Adult showing colorful underwings. Presumably to advertise toxicity to predators. Binky Lee Preserve, Chester Springs, PA.
Gravid female. John Heinz National Wildlife Refuge, Tinicum, PA.
Egg mass on a tree. The surface is a waxy substance that covers several rows of eggs. John Heinz National Wildlife Refuge, Tinicum, PA.
Third-instar nymph. Goshen Trail, Newtown Square, PA.
Three adults on a tree. Trees can have thousands. Binky Lee Preserve, Chester Springs, PA.
Sap oozing from feeding site wound. Ailanthus tree. Rose Tree Park, Media, PA.
Slick at base of Ailanthus tree caused by dripping honeydew (sugary excrement). Rose Tree Park, Media, PA.
Adult caught in spider web. Hildacy Preserve, Media, PA.

Below is a map showing the distribution of spotted lanternflies in North America as of October 3rd, 2019. Here’s a current map. To add a sighting, please sign up for iNaturalist (free) and post a photograph.

Here’s what the distribution is likely to be in the future (per Wakie et al. 2019):