Wireworm (Click Beetle Larva) Identification Notes

Underside of the head of a wireworm (click beetle larva)
Photo by Brad Sylvester, copyright 2012

One of the things I really enjoy about the "What Lives in my Yard?" project is that it forces me to take a closer look at the animals I find and to discover relationships between them (and the flora of my yard). For example, as a kid growing up in New England, click beetles are quite familiar. I recall finding them and placing them on their backs and waiting for them to "click." The unleashed elastic force of their click would not only make an audible noise, but would pop them quite high up into the air.

As an avid gardener, I am also familiar with wireworms. The hard-bodied, little, orange caterpillar-like larvae that are often found in garden soil that is rich in organic material. I never would have suspected that they were actually the same animal. Wireworms are click beetle larva.

Wireworm measuring 26mm (1") in length
Photo by Brad Sylvester, copyright 2012.

I am sure that I have click beetles on my property here in southern New Hampshire. I have seen click beetles here, but don't recall specifically seeing any other species. At any rate, I'll need to identify the larva itself, and then look for the specific adult form of the same beetle later in the season.

I can start with the click beetle family (Elateridae) and work down the taxonomy tree from there. There are seven sub-families of Elateridae listed at Bugguide.net. Clicking on these, however, nets us photos of adult click beetles, and while bugguide.net does have some pictures of click beetle larvae, there are relatively few with positive identifications and I could not find a single one that matched the tail appendages of my specimen.

Top view of the tail end of the unknown wireworm
Photo by Brad Sylvester, copyright 2012.

One of the first things that I discovered as I began searching through other sources is that wireworms are a significant agricultural pest. The larva live and feed in the soil for 2-5 years before pupating and turning into an adult click beetles according to an Oregon State University web page. They eat roots, tubers, germinating seeds, and sometimes other insects and can cause significant damage to garden crops such as peppermint, potatoes, corn, strawberries and other food crops. Note that this particular specimen was found in the soil of what was a strawberry bed ( a fact which may help in the identification).

As an agricultural pest, of course, pesticide manufacturers are among the major sources of information about this insect. Syngenta has a complete field guide for wireworms detailing their behavior and life cycle along with copious amounts of data about almost every aspect of their existence --except determining exactly which species they are. As far as the Syngenta guide is concerned, wireworms are wireworms and they're all bad. This is despite the fact that the majority of wireworms eat decaying matter and a few eat other insects.

Side view of tail end of wireworm showing a single, central
proleg
Photo by Brad Sylvester, copyright 2012.

Interestingly, though, once they do pupate and metamorphose into click beetles, they cease to be a problem and no longer eat agricultural crops at all. Syngenta also provides a simple technique for determining whether you have wireworms in your fields. Just plant a small ball of dough and check it a few days later. Wireworms, they say, are attracted to CO2 emitted by the dough or by germinating seeds. I might try this one day to see if I can find more than one species of wireworm.

Another problem with trying to identify insects using field guides like the National Audubon Society Field Guide to North American Insects and Spiders  is that they are not truly comprehensive in scope. They may list a few representative species from a taxonomic Family or Genus, but many are left out. From my own experience, I know that the Eyed Click Beetle is not the only one found here, but it is the only one listed in the Audubon guide.

This wireworm had one set of legs on each of the first three
segments after the head.
Photo by Brad Sylvester, copyright 2012.

According to Majka and Johnson as published in Zootaxa, however, there are 965 individual species of Elatiderae in North America of which only about 20% have described larva. Granted that not all of them are found in New Hampshire (Majka and Johnson list 91 New Hampshire click beetles) that still leaves a lot of work (and perhaps a nearly impossible task) for an amateur entomologist like myself in trying to identify the one specific species I have found, especially since it is a larval form.

The personal web page on wireworm research of Wim Van Herk, says "A little research into the classification of the Elateridae will likely lead to both confusion and frustration." Herk notes that depending upon which expert one consults, Elateridae are divided into either 3, 7, or as many as 18 subfamilies.

Face of the wireworm
Photo by Brad Sylvester, copyright 2012.

One way to identify an insect when you have only a larva and only have resources to identify the adult form, is to keep it alive in captivity until it metamorphoses into the adult form. When it spends 2-5 years in the larval form, however, that can be problematic. Another option might be to look and see where I found the larva to see if I can find adult beetles as well. The research suggests that adults will often be present overwintering in the same locations as the larva, although that would be more circumstantial than conclusive evidence. I could also keep the wireworm in captivity and offer it several food sources, strawberry roots and grubs, for example to determine what this particular species eats, which might narrow down the choices.

It seems that wireworm or click beetle larva species identification is a highly specialized field and certainly beyond my skills at present. I have, however, included some photos that show details an expert might use to identify the specific species, if you know one, please send them this way.

The best I can do for now (with help from bugguide.net) on the taxonomy of this wireworm is:

Side view of wireworm showing spot, vertical line, and
horizontal crease on each body segment
Photo by Brad Sylvester, copyright 2012.

Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Coleoptera (Beetles)
     Sub-order: Polyphaga
Superfamily: Elateroidea (Click beetles, fireflies & soldier beetles)
     Family: Elateridae (Click beetles)
          Subfamily: unknown
Genus: unknown
Species: unknown
         

Which One is a Harmful Invasive Species?

Five animals found while turning and sifting the soil in
my garden to remove an old strawberry bed.
Photo by Brad Sylvester, copyright 2012.

One of the tasks I had to take care of today was pulling out an old strawberry bed to prepare the plot to become a vegetable garden this year. I moved a number of new strawberry plants to a new plot last fall. Pulling out the old plants involves shoveling and sifting roots out of the soil. Well any good garden soil is home to a community of organisms and mine is no different.

As I turned over the soil and pulled out the old roots and plants, I found a number of tiny creatures living in the soil and I put a few of them aside to detail for this blog. Each will get its own entry, but I just wanted to take a minute to show you what I dug up. Mind you I wasn't really searching carefully and I undoubtedly missed a number of smaller creatures.

Nevertheless, there are five distinct animals in the picture. Although, to be fair, it's possible that fewer than five species are represented if any of the grubs are larval beetles. I don't think they are, because I'd expect each species from a given sample plot to be in close to the same stage of development at this point.

Without going into research to formally identify theses species, I can tell that at least one of them is an invasive species to New England brought over from either Europe or Asia (depending upon which of several species it turns out to be) and is potentially a harmful invader to forests like those in my backyard. Which one is it? Believe it or not it's the earthworm although there may be others in this group as well. I haven't closely examined or identified them yet, but the smaller white grub in the top center of the picture could be a Japanese beetle larva which would make it a harmful invasive species as well.

While earthworms might be good for the garden, several common varieties are quite bad for forested eco-systems, but I'll dig into that a bit more on the individual species page when I post it.
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Spring Peeper (Pseudacris crucifer) - The Cross-bearing Frog

This little climbing frog was making its way up the glass
panel of one of the doors to my house on a rainy evening
in April.
Photo by Brad Sylvester, copyright 2012.

One of the signature sounds of the New England forest is the evening chorus of spring peepers. Unless one goes traipsing through the woods at night to find the pond or vernal pool from which their spring serenade erupts, however, they can be difficult to find. Unless, that is, they come almost literally knocking on your door as this one did.

As soon as you see the little suction pads on the toes, you might think tree frog, but there are three different New Hampshire frogs that might have feet like this and be agile climbers. The gray tree frog is one, the wood frog another, and the third is the spring peeper.

Tree frogs have a very distinctive dark marking under their eyes that makes them easy to rule out in this case. That leaves the gray tree frog or the spring peeper.

Spring peeper (Pseudacris crucifer) found in my yard on
April 23, 2012.
Photo by Brad Sylvester, copyright 2012.

This frog measures about an inch long and is predominantly brown on the upper side which could fit either species. When we look at the Latin name for spring peeper, however, we get a stronger clue to the identity of this particular specimen. The spring peeper is Pseudacris crucifer in Latin. It's another of those species which has been reclassified in recent years. It was formerly called Hyla crucifer. In any event, it's the crucifer part of the name in which we're interested.

Crucifer translates to cross-bearing. If we look at the back of our little frog we see that it has an elongated "X" or cross pattern. That, along with the frog's other characteristics makes this frog a spring peeper. The X shaped markings on the back of spring peepers vary pretty widely. Some may be an ordinary X, others like our specimen may have a long straight connection in the middle, and on some, one or more of the "legs" of the X may be broken or interrupted (also present in our frog).

Spring peepers are small frogs, measuring between .75 and 1.5 inches in length in resting position (as shown in photos), according to the NH F&G Dept. They can be tan, brown or gray.

A good resource to hear the spring peeper call and that of other North American Frogs is Sounds of North American Frogs (downloadable version from Amazon) or click the image below for the CD version.  


Quick Facts about the Spring Peeper (Pseudacris crucifer):

Diet: The spring peeper is an insectivore subsisting on small insects.

Habitat: Spring peepers live in marshes, ponds, vernal pools, and wet meadows and forests.

When is it here? The spring peeper lives in New Hampshire all year round.

Where does the spring peeper go in winter? The spring peeper hibernates during the winter months. It seeks cover and can be found hibernating under moss, fallen logs, loose tree bark or matted leaves according to NHPTV and the NH F&G Dept.

Reproduction: The spring peeper female lays up to 1000 eggs each spring. Each one is individually attached to plants under the surface of the water (as opposed to the large egg masses laid by some frog species). NHPTV says the eggs take 6-12 days to hatch. My guess is that the range depends mostly upon temperature and possibly oxygen content of the water surrounding them, but that's only my guess. A controlled experiment to determine if this hypothesis is correct could be conducted if eggs from a single batch could be kept in water at varying temperatures and both with and without aeration.

Spring peepers, of course, hatch as small tadpoles. They'll first add hind legs, then front legs as they absorb their tails into their body to become adult frogs. NHPTV says this happens during "late summer." If you are able to track the evening chorus of spring peepers to a particular pond in the evening, you might revisit it throughout the summer to watch the progress of the tadpoles as they develop.

Lifespan: National Geographic estimates the lifespan of the spring peeper at three years in the wild.

Predators - What eats the spring peeper? Although the spring peeper is well camouflaged, many, many different animals will eat them if given the opportunity. A variety of birds from great blue herons to domestic chickens, foxes, raccoons, snakes, large fish, domestic cats and dogs, and many other animals all eat small frogs such as the spring peeper in New England.

Taxonomy of the Spring Peeper:

Kingdom: Animalia
Phylum: Chordata
Class: Amphibia
Order: Anura
Family: Hylidae
Genus: Pseudacris (formerly Hyla)
Species: Pseudacris crucifer (formerly Hyla crucifer)

Red Fox (Vulpes vulpes) Kits (not in my yard)

Baby red fox spotted in Strafford, NH
Photo by Brad Sylvester, copyright 2012.

Yesterday, I happened to spot three baby red foxes, known as kits. They are not located in my yard, a fact which I'm sure would be good news to my chickens, but they are in my town, Strafford, NH. They were just too cute to exclude from the blog.

I saw three kits, but did not see any adult foxes with them. They were playing outside the opening to their den. The mother was undoubtedly just inside keeping a watchful eye and ear on them as they played. I took these photos using an 840mm equivalent zoom lens at twilight, so I apologize for the poor quality of the images, but it was the best I could do under the circumstances.

I was standing about 50 yards away from the kits when I took the pictures. They took no notice of me whatsoever, which is just the way I wanted it. I do not want to either make the mother fox feel as though her den is not safe or acclimate the babies to the presence of humans so I made sure to keep a good distance. For the same reason, I will not divulge the exact location of the den. Although, I may return under better light conditions to take more photos from an equally distant vantage point, I will not approach the den or any wild fox.

Although it is looking in the direction of the camera, the
red fox kits took no notice of me as I watched from 50 yards
away.
Photo by Brad Sylvester, copyright 2012.

Foxes, especially a mother guarding a den, can be aggressive at times. If you should see one, observe from a long distance using binoculars or a spotting scope. Never approach a wild fox. If it appears injured and you think it might need aid, call a NH Fish and Game Department Wildlife Conservation Officer.

It is highly likely that red foxes do frequent my yard, but until I can photograph or provide other direct evidence, they don't get on the list of what lives in my yard.




At times, the baby foxes seemed to disappear as they played in and around the opening of their den.
Photo by Brad Sylvester, copyright 2012.