''Archipsocus nomas'' is a web-spinning barklouse, a psocid in the insect family Archipsocidae. It is found in the southeast of the United States, living gregariously on trees, feeding on

lichen A lichen ( , ) is a hybrid colony (biology), colony of algae or cyanobacteria living symbiotically among hypha, filaments of multiple fungus species, along with yeasts and bacteria embedded in the cortex or "skin", in a mutualism (biology), m ...

and

fungi A fungus (: fungi , , , or ; or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and mold (fungus), molds, as well as the more familiar mushrooms. These organisms are classified as one ...

and spinning a web that adheres to the trunk and large branches in sheets. The webs are thought to protect the barklice from

predators Predation is a biological interaction in which one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill ...

and neither the insects nor the webs cause damage to the trees.IFAS Extension
/ref>

Distribution

This barklouse is found near the Atlantic coast of the United States southwards from South Carolina and along the Gulf Coast from Florida to Texas.

Description

Both adults and

nymphs A nymph (; ; sometimes spelled nymphe) is a minor female nature deity in ancient Greek folklore. Distinct from other Greek goddesses, nymphs are generally regarded as personifications of nature; they are typically tied to a specific place, land ...

of ''A. nomas'' are soft-bodied insects resembling

aphid Aphids are small sap-sucking insects in the Taxonomic rank, family Aphididae. Common names include greenfly and blackfly, although individuals within a species can vary widely in color. The group includes the fluffy white Eriosomatinae, woolly ...

s, with long narrow antennae. The

mandibles In jawed vertebrates, the mandible (from the Latin ''mandibula'', 'for chewing'), lower jaw, or jawbone is a bone that makes up the lowerand typically more mobilecomponent of the mouth (the upper jaw being known as the maxilla). The jawbone i ...

are designed for chewing and the central part of the

maxilla In vertebrates, the maxilla (: maxillae ) is the upper fixed (not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front of the mouth. The two maxil ...

is modified into a slender rod which is used to brace the psocid while it grinds away with its mandibles. The forehead is enlarged and there are prominent

compound eyes A compound eye is a visual organ found in arthropods such as insects and crustaceans. It may consist of thousands of ommatidia, which are tiny independent photoreception units that consist of a cornea, lens, and photoreceptor cells which distin ...

and three

ocelli A simple eye or ocellus (sometimes called a pigment pit) is a form of eye or an optical arrangement which has a single lens without the sort of elaborate retina that occurs in most vertebrates. These eyes are called "simple" to distinguish the ...

. There are glands in the mouth from which silk can be spun. The eggs are pale gray or white, oblong and wider at one end than the other. The first

instar An instar (, from the Latin '' īnstar'' 'form, likeness') is a developmental stage of arthropods, such as insects, which occurs between each moult (''ecdysis'') until sexual maturity is reached. Arthropods must shed the exoskeleton in order to ...

nymphs are recognisable by the fact that their heads are wider than their bodies. They are wingless, miniature versions of the adult and have a pale brown head and creamy white thorax. It is unclear how many moults the nymphs undergo but in the closely related species, '' Archipsocus floridanus'', the females moult six times whereas the males usually moult five times. Later instars are darker in colour and the third instar female exhibits wing pads for the first time. There are five times as many adult females as there are adult males but

parthenogenesis Parthenogenesis (; from the Greek + ) is a natural form of asexual reproduction in which the embryo develops directly from an egg without need for fertilization. In animals, parthenogenesis means the development of an embryo from an unfertiliz ...

has not been observed in this species.Life history studies on some Florida insects of the genus Archipsocus (Psocoptera)
/ref> The adults are darker in color than the nymphs and are about three millimetres long.
/ref> Not all adults have wings, but when they do, these are transparent and held in a tent-like position above the body. Some females have longer wings than others but when the males have wings, these are always short.
/ref>

Life cycle

In the spring, female barklice lay eggs singly or in groups in crevices on the trunks of trees and cover them with debris for protection.

Hardwood Hardwood is wood from Flowering plant, angiosperm trees. These are usually found in broad-leaved temperate and tropical forests. In temperate and boreal ecosystem, boreal latitudes they are mostly deciduous, but in tropics and subtropics mostl ...

trees are chosen for egg laying, particularly evergreen oaks and

pecan The pecan ( , , ; ''Carya illinoinensis'') is a species of hickory native to the Southern United States and northern Mexico in the region of the Mississippi River. The tree is cultivated for its seed primarily in the U.S. states of Georgia ( ...

s. As the weather grows warmer, the number of insects mounts and from July to October the colonies rapidly increase in size. The sheets of silken webbing they build may cover the trunk and main branches of the tree. It is at this time of year that long-winged females are seen and these fly off to establish new colonies on other trees. By early December, populations are beginning to decline and most psocids are killed by frosts during the winter. The webs tatter and disintegrate in bad weather. Both nymphs and adults feed primarily on small crustose lichens, but also consume fungi, dead bark and organic debris. The insects overwinter as adults and occasionally as late instar nymphs on the evergreen southern live oak,

Quercus virginiana ''Quercus virginiana'', also known as the southern live oak, is an evergreen oak tree endemic to the Southeastern United States. Though many other species are loosely called live oak, the southern live oak is particularly iconic of the Old South. ...

, and cabbage palms,

Sabal palmetto ''Sabal palmetto'' (, ''Help:Pronunciation respelling key, SAY-bəl''), also known as cabbage palm, cabbage palmetto, sabal palm, blue palmetto, Carolina palmetto, common palmetto, Garfield's tree, and swamp cabbage, is one of 15 species of Saba ...

, where they are less likely to be killed by frost than on other trees. Polymorphism sometimes occurs in this species.

The web

The webs are a dense sheet of strands, each of which is finer than the silk spun by spiders. They may cover tree trunks and branches, and also sometimes occur on the sides of buildings and the leaves of palm trees, oaks and magnolias. On tree trunks, the long axis of the web is usually parallel to the trunk and the fabric contours the grooves and ridges. On branches the web may appear to originate from twig junctions. The psocids can detect vibrations in the web and take action to escape from potential predators which are usually

spider Spiders (order (biology), order Araneae) are air-breathing arthropods that have eight limbs, chelicerae with fangs generally able to inject venom, and spinnerets that extrude spider silk, silk. They are the largest order of arachnids and ran ...

s and

ant Ants are Eusociality, eusocial insects of the Family (biology), family Formicidae and, along with the related wasps and bees, belong to the Taxonomy (biology), order Hymenoptera. Ants evolved from Vespoidea, vespoid wasp ancestors in the Cre ...

s. Several species of

mite Mites are small arachnids (eight-legged arthropods) of two large orders, the Acariformes and the Parasitiformes, which were historically grouped together in the subclass Acari. However, most recent genetic analyses do not recover the two as eac ...

s and

springtail Springtails (class Collembola) form the largest of the three lineages of modern Hexapoda, hexapods that are no longer considered insects. Although the three lineages are sometimes grouped together in a class called Entognatha because they have in ...

s have been found under the web but they seem to be casual visitors, having no relationship with the psocids but also gaining protection from the web.

Behaviour

Although these psocids are gregarious, they are not

social Social organisms, including human(s), live collectively in interacting populations. This interaction is considered social whether they are aware of it or not, and whether the exchange is voluntary or not. Etymology The word "social" derives fro ...

in the sense usually used by

entomologists Entomology (from Ancient Greek ἔντομον (''éntomon''), meaning "insect", and -logy from λόγος (''lógos''), meaning "study") is the branch of zoology that focuses on insects. Those who study entomology are known as entomologists. In ...

. The female does not care for the eggs after they have been laid but the nymphs do grow up in the protective environment of their parental web, to which they also contribute silk for building and repairs.

References

{{Taxonbar, from=Q4786964 Archipsocidae Insects of North America Insects described in 1939