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Ichnuemon Wasp

Critter Files/Insects/Wasps, Ants, & Bees/Solitary Wasps
By Katja Seltmann and Blake Newton
University of Kentucky Department of Entomology

Common Kentucky Solitary Wasps:

KINGDOM: Animalia | PHYLUM: Arthropoda | CLASS: Insecta | ORDER : Hymenoptera | SUBORDER: Aprocrita (narrow-waisted wasps, ants, and bees)


This page is devoted to a large group of narrow-waisted wasps from several different families collectively known as "Solitary Wasps."  This group includes all narrow-waisted wasps that do NOT live in hives or colonies.  Most of these wasps are parasitic: parasitic wasps are solitary wasps whose offspring feed on or inside other arthropods.

There are hundreds of species of narrow-waisted solitary wasps that live in Kentucky.  Most of them are ant-like in appearance, with narrow waists and thread-like antennae.  All solitary wasps have 4 membranous wings except for a few types, such as velvet ants, which do not have any wings.  The best way to distinguish a solitary wasp from a social, hive-dwelling wasp is to observe behavior: hive wasps will stay close to their hive and return to it often during their routine; solitary wasps may have a small burrow or nest that they return to, but it will be much smaller than the hive of a social wasp.  In addition, you will rarely see solitary wasps interacting with other wasps, while hive-dwelling wasps will often communicate with one another, often by touching antennae or legs.

SIZE: Adult body length varies with species. The smallest parasitic wasps are less than 1/8th" long, the largest solitary wasps are about 2" long.

Like all wasps, solitary wasps have complete metamorphosis with egg, larva, pupa, and adult stages.  Many large narrow-waisted solitary wasps (such as mud-daubers, cicada killers, and potter wasps) build small nests or burrows in which they lay eggs.  Within this burrow, the wasp encloses an insect or spider that has been stung and paralyzed.  When the wasp eggs hatch, the tiny wasp larvae feed on the paralyzed prey items, and receive no further care from the mother.  Small internally-parasitic wasps, such as ichneumon and braconid wasps, do not build nests or burrows.  Instead, they hunt for insects, insect larvae, or insect eggs and lay their own eggs inside.  When the larvae hatch, they feed and grow inside the host.  Most solitary wasps are active in summer and fall and overwinter as eggs or pupae.

tiphiid larva feeding on a grub
Shown above is a beetle grub being fed upon by the larva
of a tiphiid wasp.  The tiphiid larvae is the smaller insect
in the picture.  (R. Bessin, 2000)

Although they are not as well-known as paper wasps, hornets, and yellow-jackets, there are many species of narrow-waisted solitary wasps in Kentucky, including hundreds of parasitic wasps.

Solitary wasps and parasitic wasps are an important component in a variety of ecosystems: almost all solitary wasp species provide insects or spiders to their larvae, either by laying their eggs in burrows provisioned with prey or by laying their eggs inside insect hosts.  Most species are very specific about the types of prey that they hunt.  Mud-daubers, for instance, pack their mud tubes with spiders.  Wasp species that are internal parasites will usually lay their eggs in only one or two insect species and are specific about which stage in the life-cycle that they attack: some species attack only larvae, some attack only eggs, some attack only adult insects or pupae.  Most adult solitary wasps feed on nectar.  Solitary wasps are found in most Kentucky habitats, from farms and lawns to forests and stream sides.

Although most solitary wasps have stingers, the stingers are not used for defense as often as with hive wasps.  A few species, like cicada killers and mub-daubers, are able to sting in defense.  Many parasitic wasps species have stingers that are only used to place eggs inside hosts and cannot be used in defense.  Because of this, many solitary wasps are fed upon by birds, spiders, and other wasps.


Because their larvae feed on other insects, most species of narrow-waisted solitary wasps are considered beneficial.  A few types, such as cicada killers, are large enough and common enough in urban areas that they are sometimes considered pests, even though they rarely sting people.  Read our ENTFact about pest Cicada killer wasps for more information.


FAMILY: Sphecidae
There are many species of Sphecid Wasps in Kentucky.  Most are shiny black or metallic blue, some with bright red, yellow, or orange markings.  The most common sphecid wasps are in the subfamily Sphecinae and are called "Thread-Waisted Wasps."   These sphecids have a long, narrow, antlike appearance.  Most thread-waisted wasps build their nests underground.  Some sphecids, often called "mud-daubers," make mud nests for their larvae which they attach to the sides of rocks and buildings.  The Cicada Killer Wasp (Sphecius specious) is also a type of Sphecid wasp.  At 1 1/2," cicada killers are the largest wasps found in Kentucky.  They are commonly seen in late summer as they hunt for cicadas which they use to provision their eggs in underground burrows.  Like many sphecid wasps, cicada killers are able to sting people, but they will not do so unless provoked.  


Thread-Waisted Wasp (R. Bessin, 2000)
Cicada Killer Wasp
Cicada Killer Wasp (R. Bessin, 2004)
Cicada Killer Burrow
Cicada Killer Burrow (R. Bessin, 2000)
FAMILY: Pompilidae
These large wasps are called Spider Wasps because their young feed on paralyzed spiders.  They generally are black or brown but some are brightly colored or metallic.  Spider wasps are common and are often observed searching for spiders on lawns.  Others can be seen moving quickly along the trunks of fallen trees, flitting their wings.  Like other stinging wasps (including Hive Wasps, Bees, and Cuckoo Wasps), female spider wasps have their egg laying device modified into an effective (and sometimes painful) stinger.  Common Kentucky spider wasps are about 1" long.
Spider Wasp
Spider Wasp (K. Seltmann, 2004)
FAMILY: Vespidae | SUBFAMILY: Euparagiinae
Solitary Potter Wasps are in the same family (Vespidae) as the social, hive-dwelling hornets and yellowjackets.  Potter wasps are named because some species construct small (1" inch) balls of mud in which they lay their eggs.  Potter wasps place caterpillars in these mud nests for their larvae to eat.  Common potter wasps are black with yellow or white markings are are 1/2-3/4" long.
Potter Wasp
Potter Wasp (R. Bessin, 2002)
Potter Wasp
Potter Wasp (R. Bessin, 2002)

FAMILY: Mutillidae
Velvet Ants are large (1" long) wasps in the family Mutillidae.  Although they are wasps, they are called ants because the females do not have wings.  Male velvet wasps usually have shiny black wings.  Velvet ants are covered in dense hair, and most species are bright red or orange with black markings, although some species are metallic green.  Common velvet ant females place their eggs in the larval and pupal chambers of bee and wasp nests.  Large velvet ants have very long stingers and are sometimes called "cow killers," but they will only sting if grabbed or if stepped on with bare feet.  

Velvet Ant
Velvet Ant (R. Bessin, 2000)

FAMILY: Scoliidae | GENUS: Scolia
Often seen on Kentucky lawns in summer, the most common Scoliid Wasps are black with orange and yellow markings and are about 3/4" long.  These wasps are sometimes called "digger wasps" because a female scoliid will dig into soil for a beetle larva.  She will then paralyze the larva with a sting and lay one egg on the larva.  She then constructs a small underground chamber for the egg and the beetle larva.  When the larva hatches, it will feed on the beetle larva.  

Scoliid Wasp
Scoliid Wasp (R. Bessin, 2002)

FAMILY: Tiphiidae
Tiphiids are shiny black wasps that are similar in size (1 3/4" long), shape, and behavior to scoliid wasps.  Like scoliids, tiphiid wasp females hunt in soil for beetle grubs on which they place single eggs.  Because they kill turf-damaging beetle grubs, some tiphiid wasps species are considered beneficial.  You can see a picture of a tiphiid larva feeding on a beetle grub in the Life Cycle section above.

Tiphiid Wasp
Tiphiid Wasp (R. Bessin, 2002)

FAMILY: Ichnuemonidae (ichnuemon wasps) & Braconidae (braconid wasps)
Parasitic wasps in the closely-related families Ichnuemonidae and Braconidae, known as Ichnuemon and Braconid Wasps, are some of the most economically beneficial insects in Kentucky.  The many species of ichnuemon and braconid wasps that live in Kentucky attack a variety of insects, including many pest species.  Ichnuemon and braconid wasps are generally antlike in appearance, usually with dark colors and sometimes with orange or yellow markings.  They are difficult to tell apart: ichnuemon wasps (1/8" - 1 1/2") are usually larger than braconids (1/8" - 3/4"), but there is much size overlap.  Many ichnuemon wasps have long "ovipositors" on the ends of their abdomens.  An ovipositor is used to deposit eggs.  Many female insects have ovipositors, but they are sometimes especially long in parasitic wasps, who use them to probe underground and inside plant material for insect hosts.

Ichnuemon Wasp
Ichnuemon Wasp (R. Bessin, 2002)
Braconid Wasp
Braconid Wasp (R. Bessin, 2002)
Ichnuemon Wasp
Ichnuemon Wasp (R. Bessin, 2000)
Although most Hymenoptera have wings, there are a few exceptions. The 2mm ichnuemon wasp pictured below is completely wingless.  Winglessness occurs in at least one species of most of the hymenopteran families, showing biologists that it is fairly common for a group of insects to evolve from winged to wingless over time.
Wingless Ichnuemon Wasp
Wingless Ichnuemon Wasp (K. Seltmann, 2004)

FAMILY: Chalcididae
These small (less than 1/4") parasitic wasps are found worldwide.  The Chalcidiae family consists of almost 2000 described species, and all have the enlarged, clasping hind legs.  These legs are used for fighting among females and clasping onto struggling hosts when a female attempts to lay an egg.  One species of Chalcididae uses these clasping hind legs to hold the jaws of an antlion (Neuroptera) while she lays an egg down the antlion’s throat!

Chalcidid Wasp
Chalcidid Wasp (K. Seltmann, 2004)

FAMILY: Chrysidiae
Commonly called Cuckoo Wasps, the wasps in the family Chrysidiae are often beautiful and metallic blue, green or red. Some species are thieving parasites (cleptoparasites) who lay their eggs in the nests of solitary bee species.  The Cuckoo wasp larva kills the solitary bee larva and then feeds on the stored provisions within the bee nest.  Like hive wasps, spider wasps, sphecid wasps, and bees, female cuckoo wasps have modified egg-laying devices which allow them to sting.  Common cuckoo wasp species are about 1/2" long.

Cuckoo Wasp
Cuckoo Wasp (K. Seltmann, 2004)

FAMILY: Megaspilidae
Very little is known about the habits of these tiny wasps, perhaps because they are at most 3mm long.  They occur worldwide and are thought to be parasites of scale insects (Coccoidea), lacewings (Neuroptera) and many fly pupae (Diptera).  The female Megaspilidae lays an egg inside a host insect and the larva develops feeding inside usually killing the host insect.

Megaspilid Wasp
Megaspilid Wasp (K. Seltmann, 2004)

FAMILY: Pelecinidae | GENUS and SPECIES: Pelecinus polyturator
With their long, thin abdomens and shiny black bodies, Pelecinid Wasps are among the most distinctive insects found in Kentucky.  These large (1 3/4" long) parasitic wasps lay their eggs inside beetle grubs.

Pelecinid Wasp
Pelecinid Wasp (USDA)

During warm months, solitary wasps are commonly found in lawns, gardens, field crops, woodlands, and weedy fence rows.  Most species fly slowly as they search for prey or visit flowers for nectar.  Although solitary wasps are less likely to sting than hive-dwelling wasps, some (like sphecid wasps) will sting when captured, so it is best to capture them with an insect net and immediately place them in a sturdy container.  Although solitary wasps usually fly slowly, they are almost always on the move, so it can be difficult to get a good picture.  The best technique is to keep your camera focused on a flower that is being visited by lots of insects - within a few minutes, a wasp will probably visit, and you can snap a picture. 


To learn more about the science of Hymenoptera taxonomy, visit the Hymenoptera - Assembling the Tree of Life web project.  This project is devoted to developing a family tree and taxonomic keys for all Hymenoptera and is part of the initiative to create an inclusive Tree of Life for all organisms.  Contributors to this project include Katja Seltmann, Kevin Pitz, Barb Sharanowski, Carlos Sarmiento-Monroy, and Mike Sharkey of the University of Kentucky Department of Entomology.

Parasitic wasps like ichnuemons and braconids are very important in agriculture because they can reduce pests numbers.  This website from Cornell University has profiles of some of the most important wasps used to control pests:

Velvet ants are sometimes called "cow killers" because it is believed that a sting from one is powerful enough to kill a cow.  Although velvet ant stings are painful, they are not powerful enough to kill a cow! 


Original document: 25 May 2004
Last updated: 2 July 2007

Pelecinid Wasp photo courtesy USDA.  Other photos courtesy R. Bessin, K. Seltmann, and B. Newton, University of Kentucky
The Kentucky Critter Files are maintained by Blake Newton, Department of Entomology, University of Kentucky.

University of Kentucky Entomology/Kentucky Critter Files/Kentucky Insects/Wasps, Ants, & Bees/Solitary Wasps