Diapheromera femorata

Geographic Range

Common walkingsticks have a broad geographic range in North America. They can be found all along the Atlantic coast and into northern Florida. This species can be found as far west as New Mexico in the United States (US) and as far north as Alberta, Canada. They are found in 38 US states the northern most being Maine in the east, and North Dakota in the west. They are the only stick insects to occur in Canada, where they are found in Manitoba, Ontario, and Quebec.

• Biogeographic Regions
• nearctic nearctic
  • native native

Habitat

Common walkingsticks are found in deciduous woods and forests where their preferred food sources (oak and hazelnut) are abundant. They may also be found in agricultural fields, urban gardens and residential yards.

• Habitat Regions
• temperate temperate
• terrestrial terrestrial

• Terrestrial Biomes
• forest forest
• mountains mountains

• Other Habitat Features
• urban urban
• suburban suburban
• agricultural agricultural

Physical Description

Common walkingsticks have very elongated bodies that are almost cylindrical. The abdomen and thorax are long and the abdomen bears a pair of single segmented cerci that resemble palps and serve as a clasper. The head is small but bears antennae that are about 2/3 the length of the body. Legs are slender and the tarsi are five segmented.

Adult males average 75 mm in length, while females are slightly larger at about 95 mm. Nymphs of the first five instars reach average lengths of about 11, 18, 25, 34, and 46 mm, respectively.

A distinguishing feature is the supra-anal plate, which is a small and membranous lobe above the anus. Their maxillae each contain a lacina with a tridentate structure. The species is apterous. Members of Diapheromera femorata exhibit square-shaped heads. Males are brown, whereas females have a hint of green to their brown color. There are other distinguishing characteristics that separate the two sexes; the femurs of males tend to be banded, their seventh abdominal segment is longer than their ninth, and they feature cerci that lack spines.

• Other Physical Features
• ectothermic ectothermic
• heterothermic heterothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• female larger
• sexes colored or patterned differently

Development

Immature forms of the species are called nymphs. When nymphs hatch they are green, only to gain brownish color when they reach maturity. The species typically undergoes five molts, however some male members of the species have been viewed to undergo four molts, whereas some females have undergone six molts. They are a hemimetabolous species, meaning that they have three life stages (egg, nymph, and adult) and do not have a pupal stage. Their life cycle is heavily dependent upon the synchronizing with host plant seasonal cycles.

Members of the species found in the northern United States and in Southern Canada tend to be biannual with a new generation every two years, whereas southern members tend to have a new generation every year. Some populations lay eggs in the fall, which then overwinter in the leaf litter and hatch the following spring. Seasonal conditions affect the lifespan of the nymph, cooler seasonal temperatures lead the nymphs to reach the adult stage faster than in warmer season temperatures. According to one study, it took 74.7 days for nymphs to reach the adult stage, whereas the next season it took 84.9 days for this to occur. In one study, hatching occurred 11 to 17 days after the eggs were ovposited. To reach the second instar stage, 9 to 12 days were needed from the first molt, and to reach the third instar, it required 13 to 16 days. To reach the last nypmh stage 14 to 15 additional days were required, and from that to molt into an adult it required 14 days. The variations between time lengths were due to climatic variation throughout the season. The first season studied was cooler than the second and due to the colder weather, the nymphs developing in the first season had one fewer instar stage. The second season required roughly 17 days to reach the fifth instar and another 19 days to become adults. The development and lifespan of nymphs is heavily dependent upon degree-days, they tend to require an average of 1835 degree-days, to become adults.

• Development - Life Cycle
• diapause diapause

Reproduction

Courtship rituals seem to be absent for Diapheromera femorata . Exact mating systems are unknown for this species. In other species of Phasmida , males will attach themselves to a female and ride on her back for several weeks until she is ready to mate. Mating tends to be rather consistent amongst members of the order Phasmida , in which the male climbs on the back of the female, passes his abdomen to hers, from either side to engage genitalia. Males of most species of Phasmida extend their abdomen down and around on the right side of the female, however, Diapheromera femorata males pass theirs down from the left side of the female. The male genitalia form an asymmetrical structure, which is slightly divided on the left side by an oblique groove, which is where the ejaculatory duct opens. The duct is positioned slightly to the right and opens at the ventral side of the insect. A chitinous plate protects the dorsal surface of the genitalia, and gives rise to a blunt horn-like process on the left side of the genitalia. Next to the median groove, on the posterior-ventral side, arises two plates, which form a clasper. The two plates form an inward facing apophysis for muscle attachment, allowing for the clasper to grab onto the female during mating.

• Mating System
• polygynandrous (promiscuous) polygynandrous (promiscuous)

Oviposition begins in late August, peaks during mid-September, and tails off at the end of September, where it continues until late October until most of the green foliage is no longer present. The process of oviposition tends to initiate between noon and 3:00 P.M., with peak activity ranging from the times of 3:00 and 9:00 P.M., thus making the process dependent upon sunlight. The females of the species drop eggs one at a time. The eggs dropping from the trees sound like of droplets of rain. The eggs overwinter on the ground amongst the leaf litter until spring when the nymphs hatch. They push through ends of the egg and then crawl up the nearest tree during the night to find food. Hatching in oak forests occurs in mid June, typically after full expansion of the black oaks ( Quercus velutina ) occurs and typically lasts throughout July, however, Diapheromera femorata hatching has occurred in September. Hatching follows a daily periodic pattern, in which it occurs from the range of 4:00 P.M. to 7:00 A.M. with peak hatching activity occurring within the time frame of 10:00 P.M. to 6:00 A.M. It has also been noted that humidity plays a strong role in Diapheromera femorata egg hatching. Hatching tends to occur when the humidity is 80 percent or higher because the moisture in the air serves as a lubricant, allowing for the nymphs to get out of their eggs easily.

• Key Reproductive Features
• seasonal breeding seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• fertilization fertilization
  • internal internal
• oviparous oviparous

This species does not exhibit parental care. Eggs are dropped, usually from great heights, down to the leaf litter where they are left to overwinter. When the nymphs hatch they fend for themselves.

• Parental Investment
• no parental involvement

Lifespan/Longevity

Currently, little information is known regarding the lifespan of common walkingsticks.

Behavior

Common walkingsticks use camouflage as their main means of defending themselves from birds and other predators. This species' physical appearance has a strong resemblance to a twig, which allows them to blend in with their surroundings. Newly hatched nymphs tend to walk up the first vertical object they encounter, see if it is a host tree for feeding, and if not they leave the object and move in a different direction. Common walkingsticks are active at different times of the day for different activities. Feeding and nymph hatching take place typically at night, where mating usually takes place during the day. Aside from mating, they are solitary creatures.

• Key Behaviors
• arboreal arboreal
• diurnal diurnal
• nocturnal nocturnal
• motile motile
• sedentary sedentary
• solitary solitary

Home Range

Territory size is currently unknown for common walkingsticks.

Communication and Perception

Communication and perception methods are currently poorly understood for this species. Individuals likely use pheromones during mating.

• Other Communication Modes
• pheromones pheromones

Food Habits

Diapheromera femorata feeds on the foliage of trees and shrubbery. They are particularly fond of oak and hazelnut trees. They are herbivorous and have mandibles to cut pieces of the leaves, stems or flowers. Newly hatched nymphs tend to feed mainly on hazel ( Corylus americana ) and black cherry ( Prunus serotina ), but in environments where these plants are not in high abundance they tend to eat white oak ( Quercus alba ). They have also been noted to consume sweetfern ( Comptonia peregrina ), various strawberry and blueberry plants, and beaked hazel ( Corylus cornuta ), from the time frame of May to mid-June. The nymphs eat by consuming all but the major veins of a leaf. Adults tend to feed primarily on black oak ( Quercus velutina ) at all times of the day, but peak feeding activity was found to occur at 9:00 P.M. to 3:00 A.M., and their feeding habits tend to include feeding on a single leaf for quite some time, stop, move about, and then begin feeding on another leaf. They are leaf skeletonizers.

• Primary Diet
• herbivore herbivore
  • folivore folivore

• Plant Foods
• leaves
• flowers

Predation

Several insectivorous bird species are predators of Diapheromera femorata including crows and American robins . Common walkingsticks show a remarkable ability for regenerating legs that are lost by attacks from predators. When predators are present, they remain motionless with their legs close to their bodies, thus resembling a twig.

Diapheromera femorata eggs are similar to that of other Phasmid eggs in which they greatly resemble seeds of various plants, and in the case of D. femorata they resemble seeds of legumes. This may be a defense mechanism, the eggs contain a capitulum, a structure that resembles a plant eliasome, which attracts various species of ants. In other species of stick insects, the ants take the egg thinking it is a seed, remove the capitulum as food, and discard the rest of the egg at the bottom of their nest, thus protecting the egg from outside parasites or predators.

• Anti-predator Adaptations
• mimic
• cryptic cryptic

Ecosystem Roles

Diapheromera femorata is a voracious herbivore that can cause significant defoliation when populations numbers are high. During outbreak years, this species may cause entire tree branches to die. So far, insectivorous birds consume enough during outbreaks to sufficiently control the damage. Abundance of prey items during outbreaks may result in population booms for the insectivorous bird species that consume them. Diapheromera femorata females prefer certain tree species (black cherry, black and white oaks) as hosts to lay their eggs. Several species of parasitic insects utilize Diapheromera femorata as a host. The wasp species Mesitiopterus kahlii is a parasite to Diapheromera femorata eggs. Two species of flies, Biomya genalis and Phasmophaga antennalis destroy walkingstick larvae.

Economic Importance for Humans: Positive

Currently there are no known positive affects of Diapheromera femorata on humans.

Economic Importance for Humans: Negative

Common walkingsticks are herbivores that commonly "skeletonize" leaves, or eat every part of the leaf but the vein. This causes significant damage to the trees and during outbreaks, this species may cause the death of entire tree branches. This insect species is partially responsible for the defoliation and reduction of oak forests in the Ozark Mountains of Arkansas and Missouri in the United States.

Conservation Status

The species is abundant and widespread, so no conservation methods are being implemented. If anything, future efforts may be made to reduce the population in regions suffering from significant forest defoliation.

Additional Links

Encyclopedia of Life

Contributors

Lindsay Harrington (author), Rutgers University, Dave Sannino (author), Rutgers University, David V. Howe (editor), Rutgers University, Rachelle Sterling (editor), Special Projects.

References

Arment, C. 2006. Stick Insects of the Continental United States And Canada: Species And Early Studies . Landisville, Pennsylvania: Coachwhip Publications.

Clark, J. 1974. Stick and Leaf Insects . Great Britain: Barry Shurlock.

Coulson, R., J. Witter. 1984. Forest Entomology: Ecology and Management . USA: Wiley-IEEE.

Giese, R., K. Knauer. 1977. Ecology of the Walkingstick. Forest Science , 23(1): 45-63.

Gregory, T. 2002. Genome size of the northern walkingstick, Diapheromera femorata (Phasmida: Heteronemiidae). Canadian Journal of Zoology , 80(7): 1303-1305.

Huber, B., B. Sinclair, M. Schmitt. 2007. The Evolution of Asymmetric Genitalia in Spiders and Insects. Biological Reviews of the Cambridge Philosophical Society , 82(4): 647-698.

Hughes, L., M. Westoby. 1992. Capitula on Stick Insect Eggs and Elaiosomes on Seeds: Convergent Adaptations for Burial by Ants. Functional Ecology , 6(6): 642-648.

Millron, H. 1950. The Identity of a Cleptid Egg Parasite of the Common Walking Stick, Diapheromera femorata Say (Hymenoptera: Cleptidae). The Proceedings of the Entomological Society of Washington , 52(1): 47.

Milne, L. 1980. National Audubon Society Field Guide to North American Insects & Spiders . New York: Alfred A, Knopf, Inc..

Severin, H. 1910. A Study on the Structure of the Egg of the Walking Stick Diapheromera femorata Say; and the Biological Significance of the Resemblance of Phasmid Eggs to Seeds. Annals of the Entomological Society of America , 3(1): 83-93.

Stephen, F., V. Salisbury, F. Oliveria. 2001. Red Oak Borer, Enaphalodes rufulus (Coleoptera: Cerambycidae), in the Ozark Mountains of Arkansas, U.S.A.: An unexpected and Remarkable Forest Disturbance. Integrated Pest Management Reviews , 6(3-4): 247-252.

Tilgner, E., T. Kiselyova, J. McHugh. 1999. A morphological study of Timema cristinae vickery with implications for the phylogenetics of phasmida. Deutsche Entomologische Zeitschrift , 46(2): 149-162.

Walker, E. 1922. The Terminal Structures of Orthopteroid Insects: A Phylogenetic Study. Annals of the Entomological Society of America , 15(1): 1-71.

U.S. Department of Agriculture Forest Service. Forest Insect & Disease Leaflet 82: Walkingstick. 82. Washington D.C.: U.S. Government Printing Office. 1971. Accessed March 30, 2011 at http://www.na.fs.fed.us/spfo/pubs/fidls/walkingstick/walkingstick.htm .