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Milkweed Bug LYGAEOIDS
Seed Bugs and Their Kin
Critter Files/Insects/True Bugs/Lygaeoids (Seed Bugs & Kin)
By Blake Newton
University of Kentucky Department of Entomology

KINGDOM: Animalia | PHYLUM: Arthropoda | CLASS: Insecta | ORDER: Hemiptera | SUPERFAMILY: Lygaeoidea | FAMILIES: Lygaeidae, Rhyparochromidae, Blissidae, Berytidae, Geocoridae, Pachygronthidae, etc.


Lygaeoids are a group of insects in the superfamily Lygaeoidea, which belongs to the insect order Hemiptera.  The order Hemiptera also includes assassin bugs, stink bugs, plant bugs, leaf-footed bugs, and many other insects.   All insects in Hemiptera share several characteristics, including piercing-and-sucking mouthparts, and wings which are membranous at the tips, but hardened at the base.

The superfamily Lygaeoidea includes about 15 families.  The members of some of these families are called "seed bugs," but there are many other common names as well, including Big-Eyed Bugs (family Geocoridae) and Stilt Bugs (Berytidae).  Together, all of these insects are referred to as "lygaeoids," from the name of the superfamily, Lygaeoidea. 


Until about 10 years ago, most of the insects listed on this page were considered part of the same family, Lygaeidae, and all were called "seed bugs."  Scientists recently broke the family Lygaeidae into several smaller families, including Lygaeidae (milkweed bugs and their relatives), Rhyparochromidae (which contains the long-necked seed bugs and their kin), Blissidae (chinch bugs and kin), Geocoridae (big-eyed bugs) and Pachygronthidae (contains the Oedancala genus).  All of these families were then placed in the superfamily, Lygaeoidea, along with a few other families (like Berytidae, the Stilt Bugs).

Although the new family names reflect a more accurate picture of the relationships between these insects, the changes can be confusing, especially because many field guides, websites, and entomology textbooks still treat these groups as a single family.  According to Hemiptera experts, the family Rhyparochromidae contains the only "true" seed bugs, although many insects in the other families listed on this page are sometimes called "seed bugs."

To further add to the confusion, there is an insect called the "Western Conifer Seed Bug," Leptoglossus occidentalis, which belongs to the family Coreidae (Leaf-footed Bugs).  It doesn't belong to any of the families on this page.

Visit this page from the Australian Faunal Directory to read more about the superfamily Lygaeoidea and the families that it contains.


There are many body shapes, sizes, and colors represented in the Lygaeoidea superfamily, but they have a few things in common.  Many lygaeoids are relatively slender with subdued color patterns, but several common species are brightly colored.  Lygaeoids are easily confused with members of other Hemiptera groups, especially plant bugs (family Miridae) and leaf-footed bugs (family Coreidae).

The best way to identify most lygaeoids is to examine the veins in the membranous portion of the outer wing.  In most lygaeoids, there are only 4 or 5 simple veins here, while other types of hemipterans have a different pattern.  This is not true for lygaeoids in the family Berytidae (the Stilt Bugs), but insects in Berytidae are unlikely to be confused with any other bugs.

Disrinctive wing veins of a typical seed bug
Wing of a typical lygaeoid: roll mouse over the wing to
highlight the distinctive vein pattern (B. Newton, 2006)
A microscope and a detailed scientific key (such as the key to the families of Hemiptera found in the 2004 edition of the Introduction to the Study of Insects by Borror and Delong) is need to accurately distinguish the different lygaeoid families, genera, and species from one another.  However, the most common members of each family are pictured below, and with a little practice they can be recognized without a microscope.
SIZE: Body lengths up to about 3/4" long

Like all Hemiptera, lygaeoids go through a simple metamorphosis with egg, nymph, and adult stages.  During warm months, most female lygaeoids lay eggs on plants or insert eggs into plant tissue.  The eggs hatch soon afterward.  Lygaeoid nymphs look like small, wingless versions of the adults.  As they grow, the nymphs molt (shed their skins) several times before turning into full-grown adults.  Most lygaeoids spend the winter as adults or large nymphs.

Nymph of a Milkweed Bug
Nymph of a Milkweed Bug, family Lygaeidae (B. Newton, 2005)

Most lygaeoids are herbivores that use their mouthparts to suck fluid from plants and seeds.  Some of these plant-feeding species are "generalists" that feed on a wide variety of plants, while others (like milkweed bugs) are "specialists" that feed on only a few species.  Some lygaeoids, especially the Big-Eyed Bugs (family Geocoridae) are predators that live on low-growing plants where they capture and eat aphids, caterpillars, and other insects.  In Kentucky, lygaeoids are found in agricultural habitats, gardens, fence-rows, the forest edge, and any place that is sunny with low-growing vegetation.  Lygaeoids are sometimes prey for spiders, assassin bugs, birds, and other creatures, but most lygaeoid species receive some protection from predation because of foul-tasting, defensive chemicals that they receive from their food plants.


Although some lygaeoids are predatory and are considered beneficial, a few of the plant-feeding species are serious pests.  In particular, the Chinch Bug, Blissus leucopterus, is sometimes a serious pest of grain crops and in lawns.  Read more about pest chinch bugs and their control at this Ohio State University factsheet:


FAMILY: Lygaeidae  | GENERA: Oncopeltus, Lygaeus
In Kentucky, the most well-known members of the family Lygaeidae are the Milkweed Bugs.  There are two common milkweed bugs in Kentucky.  Both are sometimes found in large numbers feeding on the sap of milkweed plants in the summer and fall in Kentucky.  Milkweed sap is toxic to most organisms, but milkweed bugs are immune to the poison and store it in their bodies to protect against predators.  The Large Milkweed Bug, Oncopeltus fasciatus, shown below, is about 3/4" long with a bold black-and-red color pattern.  Not pictured is the Small Milkweed Bug, Lygaeus kalmii.  It is about 1/2" long, but is otherwise similar to the large milkweed bug in appearance and behavior.  A milkweed bug nymph is pictured above.

Large Milkweed Bug, Oncopeltus fasciatus
Large Milkweed Bug, Oncopeltus fasciatus (R. Bessin, 2001)

FAMILY: Rhyparochromidae  | GENUS and SPECIES: Myodocha serripes
The family Rhyparochromidae contains the only "true" seed bugs.  The most well-known species in Rhyparochromidae is the Long-Necked Seed Bug, Myodocha serripes.  This distinctive seed bug is very common in gardens, lawns, and agricultural habitats in Kentucky.  It is about 3/8" long.

Long-necked seed bug
Long-necked seed bug  (B. Newton, 2006)

FAMILY: Blissidae  | GENUS and SPECIES: Blissus leucopterus
The Chinch Bug, Blissus leucopterus, is a small (1/4") insect that feeds on grasses, including lawn grasses, corn, and related plants like wheat.  It is sometimes a serious pest, as mentioned above in the Pest Status section.  It is the most well-known member of the family Blissidae.  Other members of this family have a resemblance to the chinch bug, although some species are larger.

Chinch Bug, Blissus leucopterus
Chinch Bug, Blissus leucopterus (Image courtesy USDA Photo Set)

FAMILY: Pachygronthidae  | GENUS: Oedancala
The bugs in the genus Oedancala may be the most frequently encountered insects from the family Pachygronthidae that occur in Kentucky.  The one pictured below is probably Oedancala dorsali, and it was about 1/4" long.  Little is known about this bug (or others in the family), but it is sometimes found in moist, low areas where it is believed to feed on the seed heads of grasses and sedges.  

Pachygronthid bug in the Oedancala genus
Pachygronthid bug in the Oedancala genus (B. Newton, 2005)

FAMILY: Geocoridae  | GENUS: Geocoris
Pictured below is Geocoris punctipes.  It may be the most commonly encountered member of the predatory Big-Eyed Bug family (Geocoridae) in Kentucky.  It is found in agricultural crops, gardens, and weedy areas where it preys on small insects and insect eggs.  It is a little less than 1/4" long.  A related big-eyed bug, Geocoris uliginosis, is also common in Kentucky.  It resembles G. punctipes, but it is generally a little smaller and darker in color.  Many big-eyed bug species are important predators of crop and garden pests.

Big-Eyed Bug, Geocoris punctipes
Big-Eyed Bug, Geocoris punctipes (R. Bessin, 2001)

FAMILY: Berytidae
Stilt Bugs have a distinctive appearance, with long, thread-like legs and antennae.  The stilt bug pictured below belongs to the genus Jalysus.  There are several species in this genus, and all are nearly identical in appearance and they are found in the same habitats.  They can be found feeding on tomatoes, tobacco, gourds, and related plants, although they do not cause significant damage and are not considered pests.  A few stilt bugs may also be partly predatory.  Note that the stilt bug family, Berytidae, is the only family on this page whose members were not once a part of the family Lygaeidae.

Stilt Bug, Jalysus sp.
Stilt Bug, Jalysus sp. (B. Newton, 2005)

Although lygaeoids are fairly common, they are sometimes difficult to find, especially species with brown or gray color patterns.  Look for them in think, sunny vegetation.  Lygaeoids can almost always be captured in a sweep net when used on a hot day in sunny, low-growing plants.  Large and small milkweed bugs are common and easy to find on milkweed plants.  Stilt bugs are common on tobacco and tomato plants in the summer.

Although most adult lygaeoids are able to fly, and can run quickly at times, they will usually remain still long enough to snap a picture as long as they are not disturbed, especially on a summer morning before the heat of the day arrives.  Milkweed bugs, in particular, will often remain still as long as they are not touched.


Before it was broken into several families, the seed bug family Lygaeidae had the second-most number of species in the order Hemiptera.  The plant bug family, Miridae, has the most species.


Do you know any myths, legends, or folklore about seed bugs and their kin?  Let us know if you do!


Original document: 4 Aug 2006
Last updated: 23 May 2007

Photos courtesy R. Bessin and B. Newton, University of Kentucky, except Chinch Bug, USDA Photo Set; used with permission
The Kentucky Critter Files are maintained by Blake Newton, Department of Entomology, University of Kentucky.

University of Kentucky Entomology/Kentucky Critter Files/Kentucky Insects/True Bugs/Lygaeoids (Seed Bugs & Kin)