Wednesday, May 1, 2019

Tawny Emperor and Hackberry Butterflies

Tawny Emperor
Nearly everyone loves butterflies, especially bright flashy ones like tiger swallowtails and monarchs. However sometimes beauty is found in being inconspicuous like in the case of the Tawny Emperor (Asterocampa clyton).

They are medium-sized butterflies with wingspans up to 2 5/8 inches.  Orange-brown wings contain various pale yellow spots and two black or dark brown completely formed bars. Hindwings contain black spots surrounded by orange rings. Males are smaller than females. There is a similar species, the Hackberry Butterfly (Asterocampa celtis) or the Hackberry Emperor as it is also called. This species is various shades of light to dark brown and has forewings with numerous white spots, but lack the black bars the Tawny Emperor has.

They are found east of the Rockies as well as Arizona. Commonly found in woodland habitats  where the host trees, hackberries, are found. They also share this habitat with the similar Hackberry
Tawny Emperor
Emperor. To avoid competition for the same food host they utilize the trees at different stages. Hackberry butterflies use the trees with young foliage growth, whereas Tawny Emperors wait until the foliage is older and more developed.

Adults of both species feed on rotting fruit, tree sap, carrion, and dung. They rarely nectar at flowers and when they do, they do not do so like other butterflies. They don't land on flowers, collecting pollen on their feet and bodies which can be transmitted to other flowers. Instead they take nectar without landing on the flower effectively "stealing" the sugary substance without providing any pollination benefits to the plant.

Hackberry Emperor feeding on watermelon
Males typically perch in sunny locations waiting for passing females to mate with. Once a mate has been located the female will lay eggs singularly or in small clusters on the leaves of hackberry trees. The feeding behavior of the caterpillars will not cause any serious damage to the tree. Caterpillars will overwinter in rolled leaves on the ground at the base of host trees. In the spring, the caterpillars must climb the trees and begin feeding again until they are ready to complete their lifecycle.

The Hackberry emperor shares a similar mating strategy, males also perch for females, but are easily distracted by flashy objects. Anything shiny, or bright will often lure them away from their perch. Once a mate is located though, the female will lay eggs on the host in small clusters or singularly. If the caterpillars occur in large enough numbers their voracious appetites will defoliate a tree in short order, but this behavior is not known to kill the trees. Overwintering caterpillars will finish development in the spring.

Hackberry Emperor

Hackberry emperors are much more common than their cousin the Tawny and are frequently encountered in large numbers in woodlands containing the host trees. They often land on humans, sometimes several at once, trying to lap up salty sweat from our skin. They don't seem to scare easily like most butterflies when humans approach.

Hackberry Emperor

While many of us prefer bright, flashy colors and brilliantly beautiful butterflies, I say beauty is in the eye of the beholder. For the those of us who fall in the latter category, subtlety suits us just fine.

Tuesday, January 15, 2019

Fork-tailed Bush Katydid

If the sunshine and heat don't tell you its summer, the abundance of insects will. Especially the large, calling insects like cicadas, grasshoppers, crickets and the ever popular katydid. The incessant, buzzing call of "Katy-did, katy-didn't" just screams summer nights!

Can you tell I am wishing for the warmth of sunshine and the heat of summer? It's only January and after two major snow falls in the past 6 weeks, and one more on the way for this weekend, I am officially over winter!

Missouri is home to numerous specie of katydids, and the most common may be the Fork-tailed Bush Katydid (Scudderia furcata). They are bright green and reach about 2 inches in length. Late summer or early fall specimens are often highly variable in color and may be reddish-brown, brownish, pink or reddish. There are also dark, dull green varieties, but the most common color is bright green. Males have a split "tail" on the tip of the abdomen called a furcula that is key in identification. This appendage is where their species name of furcata came from and helps identify them from other similar species. Females have a long appendage extended from their abdomen as well, called an ovipositor, that is used in egg laying. They use this appendage to deposit their eggs at the edge of leaves between the layers, but may also lay eggs on twigs or leaf surfaces. Thousands of newly hatched nymphs begin appearing in late spring. They are born looking much like their adult counterparts, they lack wings and sexual appendages. After 5 or 6 instars (molts) they will reach adult size, sometime in August.
This species is widespread throughout the United States and may be the most commonly encountered katydid in their range. They are typically found in meadows, open fields and in brushy, weedy areas near woodlands.

They feed on a variety of weedy vegetation, but seem to love citrus. Their invasion of citrus groves can make growers cringe as they watch these munchers gnaw holes in their profits. They typically chew a single hole in the rind before moving onto the next piece of fruit. This ruins the fruit for human consumption rendering it unmarketable. Fortunately this is an extreme situation and would only be a serious problem if their numbers are excessive. Usually they are content to feed on grasses and weeds, and one could even argue their feeding habits control noxious weeds by preventing them from reaching the seed dispersal stage.

Their eyesight and camouflage is excellent and they are virtually impossible to see among the vegetation unless you happen to see them move. You are far more likely to hear one before you see it. They will spot you first, and disappear on the underside of a leaf. If you continue to pester them they will fly away on strong wings. Handling one is not advised. If too severely harassed they will bite to defend themselves. Their bite feels like a painful pinch, not likely to break the skin, but unpleasant just the same.

Katydids are important to the environment as a food source for numerous species of animals. Foxes, raccoons, opossums, skunks, coyotes, rodents, birds, snakes and frogs all make use of katydids as a protein packed meal. 

Each species of katydid, just like other singing insects, has their own unique song. If you are patient and inclined to do so, you may learn each call and identify them based on sound without ever spotting them. Sound is produced by something called stridulation. Males use the rigid edge of the right wing and move it across the comb-like portion of the left wing. The rubbing of these two wing portions creates the unique call we are all familiar with.

Nothing speaks to summer quite like the call of the Katydid!