Small World Discoveries

HEMIPTERA > HETEROPTERA > PENTATOMORPHA > PENTATOMOIDEA > Cydnidae

As their colloquial name suggests, these ground-dwelling shieldbugs can often be found burrowing into loose substrate around the base of their respective food plants, as well as being seen feeding higher on the plant.  

Eight species occur in Britain, although only three are regarded as common and, even then, are mainly local across central and southern regions, rather than widespread. The remainder are categorised as 'nationally scarce' or rare in the case of the critically endangered Cornish Shieldbug [Geotomus punctulatus].

They are generally quite small, ranging from 3-4mm up to the largest species that may reach 8mm or even 9mm. They are predominantly black with few markings and have a somewhat beetle-like appearance. Their legs are stout and spiny, good for digging, and their tarsi are three-segmented.

Their small size, colour and behavioural habits makes them very unobtrusive and easily overlooked. I've finally managed to add a second species to my list, but still have one to go.

The Bordered Shieldbug [Legnotus limbosus] is around 4mm long and is very similar to the much rarer Heath Shieldbug [Legnotus picipes], but is easily distinguished by having a pale edge to the corium that extends almost to the brown wing membrane, whereas with the Heath Shieldbug it is confined to the front third. Both species are associated with bedstraws, but in very different habitats. I would have thought that the Heath Shieldbug could have been found locally but, according to the NBN Atlas, they haven't yet been recorded from Dorset. The not dissimilar Down Shieldbug [Canthophorus impressus] has though, only a handful of times as it's another 'nationally scarce' species, but it's definitely one to look out for on chalk grassland.

The distinctive Pied Shieldbug [Tritomegas bicolor] is the most attractive because of its white markings. It's probably the most common species in this group and used to be the easiest to distinguish, but now has to be looked at carefully as a recent colonist, the Rambur's Pied Shieldbug [Tritomegas sexmaculatus], first recorded in Kent in 2011, that is now slowly extending its range, has to be considered even though, at present, it hasn't been recorded further west than Surrey.

And then there's the Forget-me-not Shieldbug [Sehirus luctuosus], which is the other so-called common species I've yet to find. It doesn't look much different to the Bordered, Heath or Down varieties, so I'm probably not going to go out of my way to find it, but I shall try to remember to have a close look under any flowering forget-me-not (Myosotis sp.) plants I see, particularly in May when this shieldbug is most active.

Updated, Feb.25 (v.2)