Insects

Ian Stewart & Lori Athey

Now that spring is here many Delawareans are enjoying the colorful wildflowers blooming in their backyard, local parks and road sides. Unfortunately, the great majority of those currently flowering are alien weeds which were either deliberately or accidentally introduced by Europeans. These plants found themselves in a new environment with few or no natural enemies and spread rapidly across our area. Each weed produces hundreds if not thousands of seeds and an entire backyard can be riddled with them in just a few years.

The three most common yellow-flowered weeds have been covered in a previous blog (http://blog.delawarenaturesociety.org/2015/05/06/the-not-so-mellow-yellows/) and this follow-up blog highlights some of the other visually-appealing wildflowers that people may not realize are aggressively invasive aliens.

Three common backyard weeds stay low but spread rapidly to form sun-blocking carpets that inhibit or prevent the growth of any native seeds beneath them. Speedwell (Veronica sp.) is one of the first wildflowers to emerge and its four-petaled circular blue flower can be seen as early as March. There are several species of speedwell but most are alien. Ground ivy (Glechoma hederacea) produces dozens of tiny purple flowers and spreads by underground rhizomes which makes it especially difficult to control since pulling one part of the plant will not suffice. Clover (Trifolium sp.) is particularly common in farm fields, perhaps because it may have been introduced as livestock feed, but is now ubiquitous in urban and suburban settings. Clovers have three leaves, each with a distinctive white chevron, though finding one with four leaves may bring you luck! There are two sister species, the red and white clover, which are named after the color of their flower.

Speedwell (Left) and Clover (Right)

Ground ivy

Two striking members of the Mint family also stay quite low to the ground but are easily seen because they often grow in large patches. Purple deadnettle (Lamium purpureum) and henbit (L. amplexicaule, also known as clasping deadnettle) often grow together in fields and backyard although the former is much more common.

purple deadnettle

Henbit

Finally, three conspicuous white-flowered members of the Mustard family are widespread throughout the Piedmont. Garlic mustard (Alliaria petiolate) and roadside penny-cress (Thlaspi alliaceum) are both knee-high single-stemmed weeds which form large clumps in sunny areas, while hairy bittercress (Cardamine hirsute) is quite a bit smaller and branches into multiple small flowers.

Garlic mustard

roadside penny-cress

Penny-cress up close

Purple deadnettle (on left) and hairy bittercress (on right)

These alien wildflowers are especially problematic because they bloom in early spring and may have already produced seeds before householders begin mowing. Although it is an uphill battle, most weeds can be controlled by hand-pulling them before they go to seed, especially if the whole root system is removed.  Repeated early mowing or weed-whacking will deplete the weeds’ resources before they even flower. If you have a large yard or field an alternative option is to gradually convert it into a meadow with long grass and native wildflowers which is left standing throughout the winter and early spring. This helps to restrict early-growing weeds like ground ivy and deadnettle by reducing the amount of sunlight they receive.

Once you have removed the alien weeds you can replace them with native wildflowers which are much better for wildlife, especially our declining pollinator insects as well as the animals that feed on them. A perfect opportunity is the Delaware Nature Society’s Native Plant Sale which is held at Coverdale Farm in Greenville. It starts with a member’s-only day on Thursday May 2nd (1pm-7pm; though you are welcome to attend and join in person) and is then open to the public Friday May 3rd (3pm-7pm) and Saturday May 4th (9am – 3pm). Admission is free and there will be plenty of staff and volunteers present to answer any questions about plants and help you load them into your car!

The full catalog is online here but just to whet your appetite, here is a selection of groundcover plants which are tough and fast-growing and have a decent chance at outcompeting those pesky weeds!

Dry sunny location

Andropogon virginicus (Broom Sedge) grass

Coreopsis verticillata (Whorled Tickseed) perennial

Geum fragarioides (Barren Strawberry) evergreen perennial

Phlox subulata (Moss Phlox) evergreen perennial

 

Dry shaded location

Antennaria plantaginifolia (Woman’s Tobacco Pussytoes) semi-evergreen perennial

Chasmanthium latifolium (Wild Oats) grass

Geranium maculatum (Wild Geranium) perennial

Polystichum acrostichoides (Christmas Fern) evergreen fern

 

Moist shaded location

Asarum canadense (Wild Ginger) perennial

Osmundastrum cinnamomeum (Cinnamon Fern) fern

Phlox stolonifera (Creeping Phlox) perennial

Zizia aurea (Golden Alexanders) perennial

 

Moist to wet sunny location

Carex cherokeensis (Cherokee Sedge) grass

Eupatorium perfoliatum (Boneset) perennial

Iris versicolor (Blue Flag) perennial

Panicum virgatum (Switchgrass) grass

 

Ian Stewart

These are the opening words of the poem ‘To a mouse’, written by the legendary haggis-eating Scottish poet Robert Burns in 1785 (which also contains the famous line oft-paraphrased as ‘The best-laid schemes of mice and men go often askew’). Although this is an apt description of mice it is also used to refer to all manner of small, obscure and reclusive animals and feather mites fit perfectly into this category.

Most people have never heard of feather mites which is hardly surprising. They are tiny brown arthropods which spend most of their lives flattened along the vanes of bird wing feathers where they were assumed to scavenge on feather debris and oily secretions and perhaps even rasp away at the feathers themselves. However, a remarkable study published last summer (Doña et al. 2018) examined the contents of mites’ stomachs using high-power microscopy and DNA analysis and found that their main food was fungi, and perhaps also bacteria and oil produced from the birds’ preen gland. Whether this means feather mites harm their hosts or are simply commensal remains to be seen.

Birds are assumed to acquire feather mites through physical contact with their parents while they are still in the nest, although they could also pick up mites from bumping into other birds at feeders or sharing the same dust bathing sites. Mites are quite easy to see if you are holding open a bird’s wing although with the naked eye they just look like a cluster of small dots (shown below).

We gained a whole new appreciation for these creatures when Shannon Modla of the University of Delaware kindly photographed some Gray Catbird feather mites under a light microscope. The magnified views show that they are long and thin with two pairs of legs at the front of their body and two pairs at the back (image below). The darker mites on the left and below are probably older mites with a hardened exoskeleton while the paler one on the right is probably a younger mite that has just molted.

Shannon was then able to view them under a powerful electron microscope and got some incredible images of their head as well as an egg (below).

To try to gain some insights into the biology of these enigmatic creatures we have been scoring the number of feather mites present on birds handled during the Delaware Nature Society’s Bird Banding project. Our simple questions were which bird species are most likely to have mites and whether the number of birds with mites varies according to the time of year.

Our first finding was that feather mites are quite common. We examined 448 birds belonging to 48 species and found that almost half of them (203 birds from 37 species) had mites on at least one of their wing feathers. We also found the proportion of birds with mites varies a lot between species. Over 75% of the Slate-colored Juncos, House Finches and Downy Woodpeckers that we examined had feather mites yet fewer than 15% of Ruby-crowned Kinglets, Common Yellowthroats or House Wrens had them. We also found that the proportion of birds with mites stayed quite consistent across the year with a noticeable peak in May.

This year we will be gathering more data on mites from the birds we band and then try to figure out why some birds are more likely to have mites than others, and why some have lots of mites while others have very few. Is it related to their body size perhaps, or how social they are, or maybe whether their beak is small and pointed enough to preen away the mites? So watch this space for updates on this new and fascinating DNS research project!

DNS has plenty of birding opportunities coming up soon, so sign up and enjoy the outdoors!

The Great Backyard Bird Count ~ Coverdale Farm Preserve

The Great Backyard Bird Coount: Kent County Tour ~ Abbott’s Mill Nature Center

Owls and Other Winter Raptors ~ Ashland Nature Center

 

By Jim White: Senior Fellow for Land and Biodiversity

It’s not every day that a new species of animal is found in Delaware. In fact, it is very rare indeed. However, in the summer or 2015 Adam Mitchel, a PhD candidate at the University of Delaware did just that. While collecting insects in a meadow at the Ashland Nature Center for his PhD research project on the effects of invasive alien plants on native insects, Adam found several insect specimens that he could not identify.  After examining them under a microscope in his lab he could only identify them as insects belonging to the Insect Order Thysanoptera commonly called Thrips (both the singular and plural of the noun has an (s). The Order Thysanoptera are minute insects with reduced wings, most species being around 1mm long. All but a few use sucking mouth parts to feed on the stems of plants. Several species are considered pest as they can damage crops and other plants. However, the vast majority of the 6,000 or so species are not pests to humans and are valuable members of the food chain.

This species of Thrips, new to science, was discovered at the Ashland Nature Center by entomologist Adam Mitchel. It has no English common name, but scientifically it is called Konothrips polychaeta.  Photo courtesy of Dr. Mitchel, from Goldarazena et al. (2017).

These tiny insects are not often studied unless they are considered pests and information on the many non-pest species is limited. Lucky for Adam, a professor from Belgium, Dr. Arturo Goldarazena…an authority on Thrips, was visiting the University of Delaware. Adam approached Dr. Goldarazena and asked if he would look at some of the Thrips specimens that he collected.  It did not take long for the professor to realize that he had never seen some of the specimens and declared that Adam might have discovered a new species. Adam agreed to give Dr. Goldarazena the specimens to study back in Belgium.  After an exhausting investigation the new species was described and published in Goldarazena et al. (2017). Its official scientific name is Konothrips polychaeta which loosely translates to “hairy tenacious woodworms”.  At this time, there is no common English name for this new species of Thrips. However, I propose to call it Mitchell’s Thrips.

Andropogon virginicus is the host plant for the newly discovered Thrips. Is the new species found wherever this plant exists??? Photo courtesy of Dr. Mitchel, from Goldarazena et al. (2017).

Finding a new species of animal or plant is a dream for biologists – finding them right under our noses in places like Ashland is even more exciting. Adam found the new species inside the flowers of the broom-sedge, Andropogon virginicus but he believes that Konothrips polychaeta probably feeds and breeds on other grasses and sedges that are abundant in the meadows and marshes at the Ashland Nature Center and beyond. These meadow and marsh habitats have been restored and maintained at several of Delaware Nature Society sites as part of the land and biodiversity management program. The program is dedicated to the conservation and preservation of native species and their habitats.

Dr. Adam Mitchel is a native Delawarean and discovered the new species of Thrips while he was a PhD candidate at the University of Delaware. Photo courtesy of Dr. Mitchel.

Dr. Adam Mitchel is a native Delawarean. He attended St. Marks High School and received his undergraduate degrees at the University of Delaware in Wildlife Conservation, Entomology, Plant Protection, Agriculture and Natural Resources (quad majored), and earned his master’s degree in Fish and Wildlife Management at Montana State University. Adam returned home to University of Delaware to obtain a PHD in Entomology and Wildlife Ecology (concentration: Entomology) at the time of the discovery of the Thrips. Adam is now employed as an Assistant Professor of Entomology at Tarleton State University in Texas.

Reference:

Goldarazena A, Mitchell AB and T. Hance (2017) Konothrips polychaeta sp.n. from Delaware, North America, with a key to the three species of this genus. Zootaxa 4341: 445-450.

Recently, Delaware Nature Society hosted an informational session with Dept. of Ag. Environmental Scientist Stephen Hauss at Ashland Nature Center. This came after the insect was documented at Ashland Nature Center by our Hawk Watch Coordinator. There have been other confirmed sightings of the insect in Northern Delaware as well. Delaware is the second state to report the Spotted Lanternfly, which was first found in Pennsylvania in 2014.

Pumpkin carved by Delaware Nature Society Web & Graphic Design Coordinator, Christi Leeson

What is the Spotted Lanternfly?

The Spotted Lanternfly is an invasive and destructive insect native to China, India, and Vietnam and is known to attack many hosts including grapes, apples, stone fruits, walnut, willow and tree of heaven. It is also known as the hitch-hiker bug as it has traveled far and wide “hitch-hiking” on vehicles and other outdoor items.

Why is this a bad bug?

Delaware’s #1 industry is agriculture. The Spotted Lanternfly is a potential threat to a wide variety of crops including grapes, peaches, apples, and timber.

What to look for

The adult Spotted Lanternfly is 1 inch long and a ½ inch wide when resting and has a wing span of about 2 inches. The forewings are grey with black spots, and the hind wings are red with black spots. The head and legs are black, and the abdomen is yellow with broad black bands. The immature stages of the Spotted Lanternfly are small, round, and black with white spots, and develop red patches as they grow.

Spotted Lanternfly Adult

Spotted Lanternfly Adult

 

Spotted Lanternfly Nymphs

Spotted Lanternfly Nymphs

The Spotted Lanternfly egg mass can be difficult to spot due to its color and being small. A fresh mass will have a grey putty-like covering on top of them, blending in to the bark of the tree it’s on. An older mass that has hatched will be brown and look dried and cracked.

Lanternfly egg mass on a rock

Lanternfly egg mass on a rock

It is believed that the Spotted Lanternfly needs to feed on Tree of Heaven (Ailanthus altissima) to reproduce but will feed on other hosts as well.

What to do

If you see a Spotted Lanternfly in any of its stages, it is important to report the sighting. The Delaware Department of Agriculture asks that anyone who sees a Spotted Lanternfly to follow the below steps:

  1. Take a picture: With the GPS function turned on your smartphone or a camera with GPS, take a photograph of any life stage (including egg masses). Upload your photograph to Facebook or Instagram, using the hashtag #HitchHikerBug. If you don’t have GPS capabilities and/or access to social media, submit the photograph via email to HitchHikerBug@state.de.us and include your name, contact information, and the address or georeference of where the photo was taken.
  2. Collect a specimen: Suspected specimens of any life stage can be collected and placed in a vial or plastic zip-lock bag with the name and contact information of the collector and turned into the Delaware Department of Agriculture CAPS program for verification. This insect is considered a threat to some crops and early detection is vital for the protection of Delaware businesses and agriculture.
  3. Report a site: If you can’t take a specimen or photograph, send an email to HitchHikerBug@state.de.ussubmit using this form or call (302) 698-4586 with a message detailing the location of the sighting and your contact information.

For more information, See the Department of Agriculture’s Spotted Lanternfly checklist.

Other things to know

The coloring of the Spotted Lanternfly indicates that it could be toxic to dogs and there have been reports of dogs becoming ill after eating them. Pet owners should be careful to keep animals from eating the insect in any stage of its life.

Spotted Lanternfly Fact Sheet