Category: Natural Sciences

I attended a workshop focused on early detection of Spotted Lanternfly (Lycorma delicatula) (SLF) in Fairfax County. Speakers represented the Virginia Cooperative Extension, the Virginia Department of Forestry, and the Fairfax County Urban Forest Management Division.

Spotted Lanternfly is native to China, and has also been found in India, Vietnam, and Japan. Introduced in Korea in 2006, it is considered a pest in that country. The insect was first detected in the US in September 2014, in Berks Country, Pennsylvania, where it was likely imported as egg masses laid on landscaping stone. The first Virginia populations were detected in the Winchester area last year.

A hemipteran, L. delicatula is highly invasive and can expand its range rapidly; it can use at least 70 North American host species, although it has a particular association with Tree of Heaven (Ailanthus altissima). A phloem feeder, the lanternfly sucks sap from its host plant, leading to wilting and reduced photosynthesis. Spotted Lanternfly also exudes honeydew, which promotes the growth of sooty mold, further impairing the health of its host plant.

Because its American hosts include species of grapes, hops, stone fruits, and Malus, the threat of significant economic losses looms.

Egg masses are laid on the roughened, brocaded bark of A. altissima, other tree species, and even weathered stone, concrete, and metal. Spotted Lanternfly undergoes incomplete metamorphosis, the eggs hatching into nymphs that go through several instars before transforming into winged adults. It is conjectured the lanternfly extracts and isolates toxins from its ailanthus host, and hence that the bright red coloration of its later instars and adults constitutes aposematic coloration. The adult, about an inch long, resembles a colorful black-brown-and-red moth.

In Virginia, first instar nymphs for this season were observed on 26 April 2019. If you see an egg mass, nymph, or adult that you suspect to be Spotted Lanternfly, please report it via https://ext.vt.edu/spotted-lanternfly.

But, wait, there’s more! Fairfax County foresters hope to monitor possible sites where SLF might first appear, and that means monitoring populations of A. altissima, itself a non-native invasive species. It turns out that our map of ailanthus patches in the county is incomplete, especially on private property. Therefore, please report any Fairfax County observations of Tree of Heaven (Ailanthus altissima) to the MAEDN (Mid-Atlantic Early Detection Network), either via its mobile app or the web site.

In passing, David George Haskell mentioned the “news teller bee” in The Songs of Trees. Eric R. Eaton has the deets on this syrphid dipteran.

A beautiful one-frame visualization of the geology of the Mid-Atlantic by Kat Cantner, courtesy of Callan Bentley.

Some links, Creepy Parasite Edition:

• Dodder (Cuscuta sp.), a twining plant parasite, can inject bits of microRNA into its hosts, blocking gene-based plant defense mechanisms. Summary of new research by Saima Shahid et al. at Phys.org.
• We’re understanding more about how the fungus Ophiocordyceps unilateralis takes over the behavior, if not the mind, of its ant hosts, as Ed Yong reports.
  

  Once an infection is underway, he says, the neurons in the ant’s body—the ones that give its brain control over its muscles—start to die. [David] Hughes [at Penn State] suspects that the fungus takes over. It effectively cuts the ant’s limbs off from its brain and inserts itself in place, releasing chemicals that force the muscles there to contract. If this is right, then the ant ends its life as a prisoner in its own body. Its brain is still in the driver’s seat, but the fungus has the wheel.

Alonso Abugattas identifies the mystery spiders that I met two autumns ago: Neoscona sp., probably N. crucifera. He explains why they “seem to appear” in fall:

During the earlier part of the year you likely never noticed them. Not only were they much smaller as spiderlings, but they hide during the day. They would tear down and consume their webs every morning, so you often didn’t notice their webs they constructed nightly. They did this to avoid daytime predators such as birds or wasps from finding them. Mud Dauber wasps for example often sting and paralyze many of these when they’re young, stashing them in their mud nests as living paralyzed food for their own babies.

But by Fall, they’re often too big for wasps to eat. Many wasps have also concluded hunting and egg laying by this late in the year. So the spiders sometimes hang out during the day. Many birds also don’t go after them as much, having no babies to feed or they themselves leaving on migration South. Prey also gets scarcer as it gets colder, so leaving the web up during the warmer day increases the chance of a catch. Consequently, Spotted Orbweavers don’t hide as much and also don’t tear down their webs and rebuild them at night as much once autumn arrives.

Julia Franz visits the 8,000 acre Hubbard Brook Experimental Forest.