The love-hate relationship with some caterpillars can be vexing even for a nature lover

Sue Pike seacoastonline.com Published August 18 2022

I find I have to constantly keep my knee-jerk reactions to certain insects in my garden in check.  I tend to have an us vs them mentality when it comes to insects that I find feeding upon the foliage of plants I hold near and dear to my heart.  I planted a hedgerow a number of years ago that is just starting to flourish.  In it grow a variety of native shrubs-spicebush, elderberry, chokecherry, serviceberry.  The idea is to create safe harbors and food sources for native insects and birds.  Last week two different caterpillars showed up on the serviceberries.  These two caterpillars perfectly illustrate my sometimes conflicted reaction to the insects that eat my plants-a tiger swallowtail caterpillar and some yellow-necked caterpillars (Datana ministra).

Tiger swallowtail caterpillars rest during the day in webby hammocks Sue Pike photo

Tiger swallowtail caterpillars are adorable: medium-sized plump green caterpillars with a swollen thorax (the segment right behind the head, which in this case covers the head) sporting two prominent false eye spots used to scare away would-be predators.  The flying adults are large yellow and black butterflies with the dangling tails, fairly common in this area.  There are two similar tiger swallowtails found in this area.  The range of the Eastern tiger swallowtail (Papilio glaucus) extends further south and the Canadian tiger swallowtail (Papilio canadensis) further north.  To make things more confusing, these two species hybridize in central New England-so this particular caterpillar might be a cross between the two species.  Since it is difficult to distinguish hybrids from Eastern and Canadian tiger swallowtails, I have referred to this caterpillar as a tiger swallowtail-that much I’m sure of. 

Yellow-necked caterpillars are cute in their own way-dark heads, a bright yellow segment just behind the head (hence the name), with sporty brown and yellow stripes running the length of their bodies.  But they lack those engaging cartoon eyes and, more importantly, they are very gregarious-I counted at least 50 on the serviceberry bush.  Groups of ten or more were clumped on the branch tips, actively stripping the serviceberry of its outermost leaves (unlike the low-key solitary tiger swallowtail). Later this summer they will burrow into the ground to overwinter before emerging next spring as small moths.  Instead of the delight I felt upon seeing the tiger swallowtail caterpillar I immediately began planning their demise.    

Yellow-necked caterpillars are not as ‘cute’ as tiger swallowtails and are more obvious defoliators. Large groups can quickly strip branches bare of leaves. Sue Pike photo taken at littleriverphotoworkshop

If you do a search on tiger swallowtail caterpillars you’ll find lots of interesting life-history, nothing about ‘control’ since these are not considered a pest species.  Yellow-necked caterpillars, on the other hand, are considered pests.  They can cause damage to planted fruit and shade trees, but in their natural environment, in a forest for example, they do not significantly damage their host trees.  

The purpose of my hedgerow is to provide food and shelter for native species.  Both the tiger swallowtail and the yellow-necked caterpillars are doing what comes naturally, feeding on the leaves of the trees and shrubs in my hedgerow.  Both of these species provide food for birds, predaceous bugs and parasitic flies. As I considered the fate of my yellow-necked caterpillars I realized that removing them meant removing a food source for others as well as contributing to the decline of a native insect.  I figure that if the yellow-necks feed according to plan they will defoliate just the outer branches of my serviceberry bush.   If I’m lucky some robins (robins evidently love yellow-necked caterpillars) will discover them and provide a little bit of control. But if not, my serviceberry should survive this natural pruning, and hopefully next year will support even more backyard diversity.

Hopefully my serviceberries are healthy enough to withstand these yellow-necked caterpillars! Sue Pike photo

Nature News: Ominous-looking turkey vultures won’t hurt a thing

Published Feb 15 2022 in Seacoast Area newspapers and online at seacoastonline.com

This past weekend I was really worried. There were no birds at the feeders. Usually goldfinch, chickadees and all those other winter bird feeder birds are swarming to the sunflower seeds and suet. Instead, nothing.

It finally occurred to me to look around. High up, at the top of a giant white pine, were two turkey vultures. These eagle-sized birds looked ominous, like birds of prey waiting to swoop down and eat something. I could see why the regulars were in hiding.

However, unlike other birds of prey, these turkey vultures aren’t a threat to my bird feeder birds.  

I don’t know what they were doing up there, perhaps enjoying the sun, but turkey vultures are true scavengers. They feed on carrion – not goldfinch, chickadees and other small birds. They did not have designs on my birdfeeders.

One of two turkey vultures perching high up in a white pine Sue Pike Photo

Turkey Vultures almost never attack living prey

Here’s what the Cornell Lab of Ornithology has to say about their feeding preferences: “Turkey Vultures eat carrion, which they find largely by their excellent sense of smell. Mostly, they eat mammals but are not above snacking on reptiles, other birds, amphibians, fish, and even invertebrates. They prefer freshly dead animals, but often have to wait for their meal to soften in order to pierce the skin. They are deft foragers, targeting the softest bits first and are even known to leave aside the scent glands of dead skunks. Thankfully for them, vultures appear to have excellent immune systems, happily feasting on carcasses without contracting botulism, anthrax, cholera, or salmonella. Unlike their Black Vulture relatives, Turkey Vultures almost never attack living prey.”  In fact, turkey vultures are the only scavengers around here (unlike bald eagles, for example) who can’t kill their prey. Their  feet are more chicken-like than hawk or eagle-like, useless for tearing into prey. Their beaks are the powerful part and can tear through even the toughest cow hide. They feed by thrusting their heads into their prey, a good reason for their bald, turkey-like heads.  

Turkey vultures are most closely related to storks

The word raptor refers to a broad group of birds of prey – eagles, falcons, hawks and, until recently, vultures. Vultures appear to be very raptor-like. One of the shared traits of raptors is their ability to rip into prey with their powerful talons. Vultures don’t do this, they use their beaks. DNA evidence places them as more closely related to storks than to other raptors. After seeing these turkey vultures, I started looking at my chickens in a different light. Looks-wise, my chickens seem very vulture-esque. They aren’t related –beware of basing relatedness on looks!

It worries me to see turkey vultures in winter. They aren’t supposed to be here. When I entered my sighting into eBird.com (an online birdwatching database), I had to add additional comments because they are unusual this time of year. In fact, turkey vultures are relatively, geologically speaking, new to New England even in the summer. I have a 1987 bird guide in which their range doesn’t extend north of Massachusetts, but, a number of “southern” species like red-bellied woodpeckers, tufted titmice, cardinals, mockingbirds and turkey vultures have been pushing their ranges north since the last Ice Age.

New England is part of the ‘normal’ turkey vulture range in the summer, but recently, with our warmer winters (and perhaps increasing deer population) turkey vultures are lingering into the winter. These two looked healthy. With their bright red bald heads, glossy black wings and shiny white beaks they are interesting harbingers of climate change to come.

For past columns go to my archives–I update this as much as I can-I literally have hundreds out there–just need to get them into one place (here)

Nature News: Warblers are small, but colorful insect eaters

published May 17, 2021 in the York Weekly, Porstmouth Herald, Foster’s Daily and other Seacoast Media Group local papers

I have a friend who has had bird feeders for years and is fairly knowledgeable about most of the birds that visit her feeders.  However, the other day I was telling her about the warblers that were coming through my yard and she asked me what exactly a warbler is. She had heard of warblers but had never knowingly seen one at the feeder.  But, warblers are small and quick and if you didn’t know what to look for your brain might lump them in with other small birds that are difficult to identify.  Another reason my friend might have missed encountering warblers is because most of the warblers in the United States and Canada (over 50 species breed up here) don’t visit bird feeders.

Warblers are neotropical migrants lured here by our bugs.

Warblers are among the smallest birds in our woods and can be among the most colorful.  They are neotropical migrants, meaning they overwinter in the new-world tropics (hence neo-tropics) migrating to North America in the spring to breed.  Starting perhaps mid-April they have been moving into and through New England on their way north.  Why come up here?  Why leave balmy Central and South America?  Insects!  It’s black fly season! I also heard my first mosquitoes today.  The lure of a high-protein bug-diet, necessary for raising young, is what brings these insect-eaters north. 

This palm warbler is one of the many warblers that migrate through in the spring. stevemorello.com photo

What is a warbler? According to Encyclopedia Britannica, warblers are “any of various species of small songbirds belonging predominantly to the Sylviidae, Parulidae, and Peucedramidae families of the order Passeriformes. Warblers are small, active insect eaters found in gardens, woodlands, and marshes.” (According to The Cornell Lab’s Bird Academy warbler course I’m taking there are actually 8 different families of birds with the name warbler!).   When we talk about warblers here in the U.S we are referring to the new world warblers (also known as wood warblers).  The wood warblers are more closely related to orioles but got the name warbler from their physical and behavioral resemblance to the old world warblers. 

Some tips on how to identify the confusing array of warblers.

While warblers have a wide variety of colors and patterns you can learn to recognize them by their overall shape-small with narrow insect-eating bills, short to medium tails, and, as mentioned before, they are active foragers, always moving about looking for their next meal.  If you want to take the plunge, the next step is to try to identify some.  This group is notoriously difficult to identify.  Because they are so active it can be hard to get a good look so you have to train yourself to look for a variety of features–color, wing bars, eye rings vs eye lines, breast markings or patterns on the tail.  Paying attention to where they are foraging is also helpful as many have divided up available habitat into different foraging areas to avoid direct competition for food (this is called resource partitioning).  A famous example of resource partitioning is from a 1958 study by Robert MacArthur in which he described how 5 different northeastern warbler species had divided up their foraging area-blackburnian and Cape May warblers preferring the tops of trees, while black-throated green warblers stuck to the inner branches around the middle. 

Watch for new warblers to show up at feeders throughout the spring

Spring is the best time to be looking for warblers.  Just like the spring wildflowers that are welcoming in the season, the arrival of these tiny migrants to our woods heralds the warmer days to come.  And, if the bears haven’t yet forced you to take down your bird feeders some might come by to check out the suet.  We’ve had yellow-rumped warblers, blue-winged warblers and palm warblers drop by this spring and have been hearing many more in the trees. So, while I am lamenting the arrival of the black flies and mosquitoes  I am also happy about it-more bugs means more warblers.

Nature News: The Ancient Life Cycle of the Mayfly

published 05/10/2021 in The York Weekly, Portsmouth Herald and other Seacoast Media Group publications

Life aquatic-what lives under the mirror-like surface of a local stream?

I don’t know why I was worried, but I was.  While preparing to lead a stream exploration I was worried that it was too early in the season to find anything interesting in the stream.  Worried despite the evidence all around me-while kayaking last weekend my son and I had encountered flights of mayflies, the aquatic juveniles metamorphosing into flying adults all around us, ethereal sprites fluttering up from the surface of the water into the sun.  Despite the black flies that are already plaguing us in the garden. Despite the warm spring days.  So, I went down to the little river/big stream that meanders through the valley behind my house and checked to see who was out and about in the stream bed.  I found tiny water boatmen, diving beetles and tons of juvenile mayflies (aka nymphs) and so realized I could stop worrying about a lack of aquatic life.  

What lives under the glassy surface of a stream? sue pike photo

A large number of insects spend a large part of their life cycle in an aquatic environment-take mosquitoes, their aquatic juvenile stages love growing up in stagnant water.  Black flies, on the other hand, prefer to lay their eggs in faster moving streams which, because of all that movement, are better oxygenated.  Damsel and dragonflies, caddisflies, stoneflies and mayflies are also aquatic up until they molt into the adult stages of their life cycles. 

It’s a great time to look for mayflies, the water is getting warm enough to wade in and swish a net around in search of interesting critters.  And over the next few weeks (and long into the summer–the name mayfly is misleading, different species in this group emerge at different times), if you are lucky, you might encounter mayfly nymphs molting into adults and swarming over the surface of a local stream.  

Mayflies are among the most ancient orders of insects on Earth!

Mayflies are an ancient order of insect, the Ephemeroptera, a taxonomic order that was here about 100 million years before the dinosaurs.  The term “Ephemeroptera” comes from the word “ephemeral” meaning short-lived and “optera” meaning “winged” referring to the short lifespan (a couple hours to a couple days) of the winged adults whose only purpose is to mate. The aquatic juveniles, called nymphs (or naiads) pass through numerous instars (growth stages) becoming gradually more adultlike with each molt.  This is called incomplete metamorphosis.  Unlike the complete metamorphosis of something like a butterfly that has a pupal stage in which everything about the body gets drastically rearranged, the mayflies gradually change with each molt (in which they shed the exoskeleton they’ve outgrown) until they become adults.  Mayflies are the only insects to have 2 adult stages-the first winged damselfly to emerge from the water is sexually immature, this stage quickly molts into a fully reproductive adult-the final stage in its life cycle that mates and dies.  

Life aquatic: two mayflies and a diving beetle. sue pike photo

Mayfly anatomy follows the basic rules of all insects.

If you want to look for mayfly nymphs you need to know a little bit about their anatomy in order to identify them.  Mayflies have 3 body regions: a head with relatively big compound eyes, a thorax to which the 6 legs are attached and an elongated abdomen which has beautiful leaf-like (or feathery, depending upon the species) gills extending from the sides and 3 cerci (thread or antenna-like appendages) that extend from the tip. The gills can be different sizes depending upon whether the mayfly lives in still water or running water.  In still water the gills are larger than in running water because there is less oxygen in still versus turbulent water. The gills also help protect the mayflies from predators by sending water off and away from their bodies at different angles-making it hard for predators to track them. If you want to explore mayfly identification in more detail, check out the UNH Center for Freshwater Biology (www.cfb.unh.edu) or the Stroud Center (www.stroudcenter.org) for really great identification keys.

The mayfly life cycle is a beautiful, ancient cycle happening in a stream near you.

The mayfly life cycle ends (or begins-depends upon how you look at it) with reproduction.  Their life cycles are timed so that entire populations of nymphs molt and leave the water in synchrony, with the flying adults forming huge swarms over the water. The males grab passing females with elongated front legs and they mate in flight.  The female then dips down to the surface of the water to lay her eggs, when done she often falls to the water’s surface to die, oftentimes feeding fish in the process. The males don’t stick around but rather go off to the nearby land to die.  It is a beautiful, ancient cycle, not to be missed, and could be happening at a stream near you.

You can find more of my posts about backyard nature on Instagram @pikeshikes

Nature News: Dandelions will thrive as climate changes. Here’s why.

published in the York Weekly, Portsmouth Herald, Fosters Daily, York County Coast Star 5/24/2021

My Integrated Earth Science class is immersed in its last unit of the year-the science of past and future climates and the mechanisms that underlie climate change.  As an excuse to get outside I made up something called a Climate Change Impact Photo Scavenger Hunt.  The idea was to go outside and take a picture of something that you think might be being impacted by climate change and then do a little research and find the climate change story.   One of my classes really went crazy with photos of dandelions (the other class would have but I stupidly warned them away from dandelions believing them to be boring).   Turns out, dandelions provide a terrific story about how human-caused climate change is affecting dandelion growth, one that applies to many other plants that tend to be ‘aggressive’ growers already, one that teaches a great lesson about the complexity of interactions between living things and a changing environment. 

Elevated atmospheric CO2 causes dandelions to grow larger & spread faster. www.stevemorello.com photo

There have been a number of studies of dandelions in which researchers grew dandelions with elevated concentrations of carbon dioxide (twice current levels) and found that the increased CO2 caused the plants to produce more flowers and more seeds.  The seeds were heavier and produced larger seedlings that grew more robustly.  Then, in a study from Weed Science (“Reproduction of Dandelion (Taraxacum officinale) in a Higher CO2 Environment” 2007 by McPeek and Wang) I found this sentence “Furthermore, achenes from plants grown at elevated CO2 had characteristics, such as higher stalks at seed maturity, longer beaks, and larger pappi, which would increase the distance of seed dispersal by wind.”  I love vocabulary-this was just great-achenes, beaks and pappi!  

Plant Anatomy 101

One of my biggest regrets in life is that I did not like my college botany class and failed to absorb the wonderfully rich terminology used to describe the complexity of plants.  If I had, I might have already known about achenes, beaks and pappi-terms I find confusing enough I am almost afraid to write about them.  According to the Encyclopedia Britannica an achene is “a dry, one-seeded fruit lacking special seams that split to release the seed. The seed coat is attached to the thin, dry ovary wall (husk) by a short stalk, so that the seed is easily freed from the husk, as in buckwheat. The fruits of many plants in the buttercup family and the rose family are achenes.”  Sunflower and dandelion seeds are also considered achenes.  What this means is that  each little feathery tendril of a puffy dandelion seedhead is an individual fruit. Each of those achenes is an individual ovary containing one seed that is attached to the feathery, helicoptery pappi by a long slender beak.  If the beaks are longer and the pappi are larger, you have larger helicopters (or maybe parachutes? I’m not sure what to call them) that will help carry the seeds further afield.  You put all of these enhanced traits together and you get dandelions on steroids, like the bionic man, they are bigger, stronger and faster. And so, the predictions are that they will thrive in future high CO2 environments. 

Achenes, beaks and pappi! www.stevemorello.com photo

Whether this enhanced proliferation of dandelions is good or bad is all relative and is dependent upon whether you think dandelions are awesome plants or the scourges of a manicured lawn.  They were brought to this country by colonists who considered them medicinal powerhouses, curing all sorts of ailments most likely by providing needed vitamins.  They are good for your lawn-they break up the soil and help aerate it.  They are good for pollinators, a source of nectar that is available from spring through the fall.

In the end I wish I had encouraged everyone in my class to investigate dandelions from the start.  What I found as students shared their reports about climate change and dandelions was that because dandelions are so familiar it was easy  to connect to their climate change story, making the changes that are happening all around us more tangible, more real.

You can find more nature news (including informative nature minute videos about backyard nature) from me on Instagram @pikeshikes