26 October 2023

Pittsburgh’s spotted lanternfly plague (Lycorma delicatula) is mostly over after recent cold weather knocked out lots of adults. It’s not a bad year for brown marmorated stink bugs, so are the insect plagues over? Not quite. Yesterday I happened into a swarm of Asian ladybeetles.

Asian ladybeetles (Harmonia axyridis) were imported to the U.S. 35 years ago as predators for aphids, adelgids, psyllids and scales. They do a good job and they caused no trouble until they were able to overwinter starting in 1993.

Ladybeetles overwinter as adults that gather in the fall with the goal of “The More The Merrier.” Attracted to sunlight and warmth reflecting off south or southwest-facing light-colored buildings, a few accumulate and attract others by sight and smell. Pretty soon the area is crazy-busy with ladybeetles as in the photo above.

The bugs are looking for cracks in which to spend the winter. If a crack leads to a warm place indoors, that’s even better.

Once inside, the warmth can keep them active.

It is not uncommon for tens of thousands of beetles to congregate in attics, ceilings and wall voids, and due to the warmth of the walls, will move around inside these voids and exit into the living areas of the home.

In addition to beetles biting (which they do), they exude a foul-smelling, yellow defensive chemical which will sometimes cause spotting on walls and other surfaces. Most people are only annoyed by the odor of these chemicals. However, some individuals have reported experiencing an allergic reaction to the defensive excretions.

— Penn State Extension: Multicolored Asian Lady Beetle (Ladybug)

Penn State Extension has helpful advice on how to vacuum them (avoid getting them up into the machine!) at Multicolored Asian Lady Beetle (Ladybug).

The good news is: Have you seen a spotted lanternfly lately? Probably not! Winter is a great pest control system.

(photos from Wikimedia Commons; click on the captions to see the originals)

26 September 2023

Last week at Duck Hollow I found two bumblebees asleep on goldenrod. The temperature was a little chilly but the morning was bright and sunny. Were the bees waiting to warm up in the sun?

Eight weeks ago I highlighted the reason why male bees sleep on flowers in July and August. Males don’t live in a hive so they sleep outdoors. They are solitary, searching for a mate, and nearing the end of their lives.

Female bumblebees return to the hive at night if they can. In the hot months of July and August females are indoors at night. However bad weather or chilly temperatures may force them to sleep outdoors until they warm up the next morning.

So I wondered are these sleeping bumblebees male or female? I can tell with a closer look at the bees.

Female bumblebees bring food to the hive so they have pollen sacks on their hind legs. If you see a full pollen sack on a bee’s hind leg you can be sure it’s female, as shown on the right in the photo below.

A bee without pollen, like the one on the left, is either a female who delivered her pollen and has just come back for more, or it’s a male without a pollen sack.

I can see two obvious differences between male and female in these photos.

There are even more clues than this! Read all the details at Sciencing.com: How to tell if a Bumblebee is male or female.

And finally, were these two near the end of their lives?

Yes, both will die this autumn. Only fertilized queens make it through winter. Every hive starts with a lone queen in the spring.

(photos by Kate St. John)

2 September 2023

Insect activity is pretty intense in late August and September as they run out of time to eat and mate before cold weather (usually) kills them.

While vegetarian insects, such as the leaf-footed bug above (Coreidae family), munch on fruits, nuts, plants and trees, the carnivores dine on insects. Carnivores include the migrating warblers who pick tiny bugs off of leaves and branches.

Every day predatory spiders weave a gauzy web on top of these Japanese yews in Shadyside, hoping for an unsuspecting insect.

Assassin bugs (Reduviidae family, nymph below) eat many insects in their lifetime.

And if you want to red about a really creepy predator, check out this #bioPGH blog about The Super Spooky Sting of the great black wasp (Sphex pensylvanicus)

Meanwhile the vegetarian insectss are distracted by mating, as seen in this pair of Japanese beetles (Popillia japonica).

Two flies were locked in some sort of embrace on my car yesterday morning at Schenley Park. Considering the size difference I wonder if this wasn’t fratricide.

And in spotted lanternfly Lycorma delicatula) news: Yes the lanternflies are still quite present and they haven’t even begun to lay eggs yet. That’ll happen this month and next.

This week I found a milestone on the honeydew mold front: In Schenley Park on Friday I saw the white mold on top of sooty mold.

The whiteness in this photo appears to be the sun glinting off the Ailanthus tree trunk but in fact it’s white mold growing on top of sooty mold (black) on top of spotted lanternfly honeydew.

Ailanthus, “Tree of heaven,” is the host tree of the spotted lanternfly and they sure do love this one. Looking up, the tree is infested with lanternflies.

Expect more insect activity in the week ahead as bright sun and hot temperatures warm them up.

(photos by Kate St. John)