Horntail or wood wasp are any of the 150 non-social species of the
hymenopteran family Siricidae, a type of
wood-eating sawfly
Sawflies are the insects of the suborder Symphyta within the order Hymenoptera, alongside ants, bees, and wasps. The common name comes from the saw-like appearance of the ovipositor, which the females use to cut into the plants where they lay ...
. The common name "horntail" derives from the stout, spine-like structure at the end of the adult's abdomen, which is used to pierce the host's bark to allow the eggs to be inserted into the wood (the
ovipositor is typically longer and also projects posteriorly, but it is not the source of the name). A typical adult horntail is brown, blue, or black with yellow or red parts, and may often reach up to long. The
pigeon horntail (''Tremex columba'') can grow up to long (not counting the ovipositor), among the longest of all Hymenoptera.
This family was formerly believed to be the sole living representative of the superfamily
Siricoidea
The superfamily Siricoidea is an archaic group of the order Hymenoptera, consisting of six families (four extinct) of xylophagous sawflies. The group is well represented in early Tertiary and Mesozoic times, but a number of living taxa remain, inc ...
, a group well represented in
Paleogene and
Mesozoic
The Mesozoic Era ( ), also called the Age of Reptiles, the Age of Conifers, and colloquially as the Age of the Dinosaurs is the second-to-last era of Earth's geological history, lasting from about , comprising the Triassic, Jurassic and Cretace ...
times, but the family
Anaxyelidae
Anaxyelidae is a family of incense cedar wood wasps in the order Hymenoptera. It contains only one living genus, '' Syntexis'', which has only a single species, native to Western North America. Fossils of the family extend back to the Middle Jura ...
has been linked to this group as well. Siricidae has two subfamilies, Siricinae and Tremecinae. Siricinae infest needle-leaved trees
and Tremecinae infest broad-leaved trees.
There are ten
living genera placed in the family, and an additional three genera described from fossils.
Female horntails lay their eggs in trees. The larvae bore into the wood and live in the tree for up to two years, possibly more. They typically migrate to just under the bark before
pupa
A pupa ( la, pupa, "doll"; plural: ''pupae'') is the life stage of some insects undergoing transformation between immature and mature stages. Insects that go through a pupal stage are holometabolous: they go through four distinct stages in thei ...
tion.
Description
![urocerus gigas](https://upload.wikimedia.org/wikipedia/commons/7/77/Urocerus_gigas.jpg)
Members of three genera of horntail attack dying or recently killed
balsam fir
''Abies balsamea'' or balsam fir is a North American fir, native to most of eastern and central Canada (Newfoundland west to central Alberta) and the northeastern United States (Minnesota east to Maine, and south in the Appalachian Mountains to ...
and
spruce.
[Rose, A.H.; Lindquist, O.H. 1985. Insects of eastern spruces, fir and, hemlock, revised edition. Gov't Can., Can. For. Serv., Ottawa, For. Tech. Rep. 23. 159 p. (cited in Coates et al. 1994, cited orig ed 1977)] The female selects a log or unhealthy tree and settles down to bore a hole through the bark to reach the wood. The boring instrument is stiff and straight, but has a hinge that allows the female to bore perpendicular to her body axis. The insect does not push the boring tool into the wood, rather, two parts work against each other as described below. The female may make several holes before she finds wood that she considers suitable for her larva. She then lays an egg and repeats the process on other places of the same log or tree.
Once the egg hatches, the six-legged, whitish larva uses it jaws to begin excavating a long tunnel in which it will live until it is fully grown, by which time it can be up to 215 mm long. At this time, the larva will spin a silken cocoon and change into a pupa, but before this, the larva takes the precautionary measure of advancing the tunnel close to the inner bark, so that the mature, winged insect will not have to travel far through the wood and risk damaging its delicate wings, although there is a record of a ''Sirex''-infested tree having been cut into rafters which were used in building a roof and covered with sheet-lead an eighth of an inch thick. One of the rafters contained a ''Sirex'' in either the larval or pupal stage; and when the adult insect sought its freedom, it found the way obstructed by the lead. It went right through, apparently finding lead not much more difficult to deal with than bark.
Populations increase rapidly only where brood material is abundant. The life cycle usually requires two years, and adults are usually in flight from late July to early September. Wood-rotting fungi found in horntail tunnels cause very rapid deterioration of the wood and quickly reduce opportunities for timber salvage.
An ichneumon
wasp
A wasp is any insect of the narrow-waisted suborder Apocrita of the order Hymenoptera which is neither a bee nor an ant; this excludes the broad-waisted sawflies (Symphyta), which look somewhat like wasps, but are in a separate suborder. ...
(''
Rhyssa persuasoria'') lays
parasitoid grubs in ''Sirex'', which kill them.
[''Bees, Wasps, Ants and Allied Insects of the British Isles'', Edward Step (1932)]
Technological inspiration
The female wood wasp lays eggs inside trees, and its methods of doing so have inspired scientists to come up with new and safer surgical probes that they expect to be more efficient.
The wood wasp ovipositor itself contains two interlocking valves. Each valve is covered with teeth that are backward-facing, with the teeth of one valve catching onto the wood to provide resistance, and the other valve moving forward and taking a slight step. The second valve then catches the wood to provide continued resistance as the first valve moves forward. Thus by quick oscillation, the valves alternate in providing resistance and moving forward, the process itself leads in the ovipositor drilling almost an inch into the sapwood with minimal force being applied and without the ovipositor buckling or breaking.
Researchers and scientists inspired by this system have created a prototype neurosurgical probe that works on the same principle. Its needle is made of silicon, with two oscillating valves that are covered with micron-sized teeth that too face backward. This enables it to penetrate deep into the brain causing little damage.
According to the New Scientist magazine, "Unlike existing rigid surgical probes, the device will be flexible enough to move along the safest possible route, bypassing high-risk area of the brain during surgery, for example". A probe like this would considerably reduce the number of incisions necessary to access areas that are difficult to reach.
Genera
![SR UI 99-97-08 B Eourocerus anguliterreus 2015-04-17 img1a](https://upload.wikimedia.org/wikipedia/commons/b/b2/SR_UI_99-97-08_B_Eourocerus_anguliterreus_2015-04-17_img1a.jpg)
These genera belong to the family Siricidae
[
* '' Afrotremex''
* '' Eriotremex''
* '']Sirex
''Sirex'' is a genus of wasps in the family Siricidae, the horntails or wood wasps. They inject eggs with fungal endosymbionts into wood. The fungus is contained in a mycangium which nourishes it with secretions, and in turn it digests wood fo ...
''
* '' Siricosoma''
* '' Sirotremex''
* ''Teredon
Teredon was an ancient port city in southern Mesopotamia. The place could not be localized so far archaeologically, but is believed to be in Kuwait near Basra. The place is mentioned several times by ancient writers. It is said to have been founded ...
''
* ''Tremex
''Tremex'' is a genus of woodwasp in the Siricidae family. It has 33 species with a holarctic distribution. The larvae feed on hardwoods.
Selected species
'' Tremex alchymista'' (Mocsary, 1886)
''Tremex columba
''Tremex columba'', also kn ...
''
* ''Urocerus
''Urocerus'' is a genus of horntails in the family Siricidae. There are about eight described species in ''Urocerus''.
Species
These species belong to the genus ''Urocerus'':
* ''Urocerus albicornis'' ( Fabricius, 1781) (white horned horntail) ...
''
* ''Xeris
''Xeris'' is a genus of horntails found in North America and Eurasia. Achille Costa circumscribed the genus in 1894.
Synonyms
In 1987, Malkiat S. Saini and Devinder Singh circumscribed a new genus, ''Neoxeris'' upon their description of a new s ...
''
* ''Xoanon
A xoanon (, el, ξόανον; plural: el, ξόανα , from the verb el, ξέειν, , to carve or scrape ood was an Archaic wooden cult image of Ancient Greece. Classical Greeks associated such cult objects, whether aniconic or effigy, w ...
''
These extinct genera have been referred to the family as well:
* †'' Aulisca''
* †'' Cratosirex''
* †'' Cretosirex''
* †'' Emanrisca''
* †'' Eoteredon''
* †'' Eourocerus''
* †'' Eoxeris''
* †'' Gigasirex''
* †'' Liasirex''
* †'' Megaulisca''
* †'' Megura''
* †'' Pararchexyela''
* †'' Proximoxeris''
* †'' Urocerites''
* †'' Ypresiosirex''
References
External links
{{Authority control
Sawfly families