| Cydnidae | |
|---|---|
 | |
| Cydnus aterrimus Type genus for the family | |
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Class: | Insecta |
| Order: | Hemiptera |
| Suborder: | Heteroptera |
| Superfamily: | Pentatomoidea |
| Family: | Cydnidae Billberg, 1820 |
Cydnidae are a family ofpentatomoid bugs, known bycommon names includingburrowing bugs orburrower bugs.[2] As the common name would suggest, many members of the group live a subterranean lifestyle, burrowing into soil using their head and forelegs, only emerging to mate and then laying their eggs in soil. Other members of the group are not burrowers, and live above the soil layer, often in close association with plants. Several species are known as agricultural pests.[3]
Burrowing bugs range from 2 to 20 mm in length.[4] They are dark, ovoid in shape and highlysclerotised. The head is generally subquadrate to semicircular in shape, and has a pair of 5-segmentedantennae. The coxae of the legs havesetal combs, while the apices of the mid and hind coxae are fringed with rigid setae. The tibiae of the legs (also often the head and pronotum) have spines. The tarsi of the legs are 3-segmented and often reduced.[5]
Similar to other pentatomoids, Cydnidae haveglands in the thorax (adults) or the lateral part of the abdomen (nymphs) that secrete a foul-smelling mix of chemicals fordefense against predators.[6]
Cydnidae in subfamilies Cydninae and Cephalocteinae live mostly in soil and feed on roots of plants. Those in subfamilies Parastrachinae, Sehirinae and Thyreocorinae instead live on aboveground parts of plants. Adults are attracted to light and sometimes in large numbers.[5]
Cydnidae feed on sap fromphloem, unlike other heteropterans.[4]
As of 2003, there were 27 cydnid species reported as crop pests and six that feed onpeanut. Of the peanut-feeding species,Pangaeus bilineatus is the most abundant and the only one associated with feeding injury to peanut kernels.[7]
Another pest isFromundus pygmaeus, which attacksrice seedlings,sugarcane, fallen seeds ofgrasses and roots ofsoybean andclover.[8]
Some cydnids are medically important. The aforementionedF.pygmaeus facultativelysucks blood from humans,[8] whileChilocoris assmuthi can cause brownlesions on skin (usually on the feet) with its defensive secretions.[6]
BioLib includes the following subfamilies:
In some older classifications, Cydnidaesensu lato includes the subfamily Thyreocorinae (now a separate family,Thyreocoridae), which are known commonly as "negro bugs" or "ebony bugs", and/or the familiesThaumastellidae andParastrachiidae.[9][10]
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