Small World Discoveries

HEMIPTERA > HETEROPTERA > PENTATOMORPHA > COREOIDEA > Rhopalidae

This family is represented in Britain by 11 species in 7 genera, the type genus being Rhopalus with four species of which three are rare or nationally scarce. The only common species is Rhopalus subrufus. The Stictopleurus genus consists of two species, both with local distribution in areas of the south but, from the NBN Atlas at the time of writing, neither have been recorded from Dorset. Of the remaining five species, only two are regarded as common, Corizus hyoscyami and Myrmus miriformis.

Rhopalid bugs have membranous or at least partially transparent forewings, four-segmented antennae and three- segmented tarsi. Most are robust with an overall shape and form that resemble leatherbugs, but two, Myrmus miriformis and Chorosoma schillingi, are elongate with an appearance that looks more like a mirid grass bug.

The most attractive species is the Red-and-Black Rhopalid [Corizus hyoscyami]. It should be unmistakable except there are a couple of similarly marked groundbugs and the equally rare Firebug [Pyrrhocoris apterus] that need to be ruled out, however those species are all rare and extremely unlikely. The species used to be confined to southern coastal areas, but over the past few years its range extended greatly and can now be found inland throughout England and Wales, as far north as Yorkshire. Corizus hyoscyami overwinters as an adult emerging in the spring to mate. The new generation of adults usually start appearing in August or September. They prefer open areas such as grasslands, scrub, woodland rides and margins, but can also be found in some gardens and parklands.

The four Rhopalus species are rather hairy bugs with largely membranous forewings, which are typically reddish in colour. The common Hypericum Rhopalid [Rhopalus subrufus] can be distinguished from the much rarer species by the alternate dark and light bands on the connexivum and the whitish tip to the scutellum which ends in two points. The usual form has a reddish-orange head, pronotum and scutellum with some darker markings that contrast with the silvery-grey upper half of the forewings. However, there is a dull, dark grey-brown variant with dull forewings and a less striking connexivum. Rhopalus subrufus is widely distributed across central and southern Britain where it can often be found on low vegetation in scrubby areas and woodland clearings. It is associated with many plants, particularly Hypericum species such as Common or Slender St John's-wort.

As previously noted, the only other species I'm likely to encounter is the Short-winged Rhopalid [Myrmus miriformis] that looks superficially like a mirid grass bug. It is a common species in dry and damp grassland habitats. The males have two colour morphs, a green form marked with red and a brown form. The larger females (>10mm) are always green. The forewings are typically short.

I discounted the Schilling's Rhopalid [Chorosoma schillingi] when I drafted the first version of this page as it's not particularly common and, according to the distribution data at the time, had only been recorded once in Dorset in the past ten years. But, as with a number of these so-called locally scarce or unrecorded species, I did manage to stumble across one. I thought it was a grass bug, until someone corrected me and pointed out that it had ocelli, which are not present in the Miridae. As can be seen, it's a straw-coloured bug with a long body, legs and antennae, and is extremely well camouflaged when seen slowly walking around in long grass or, as here, in heather. It is usually brachypterous with the short wings reaching just beyond half the length of the abdomen. It's a local, mainly coastal species with most records coming from East Anglia, the south east and, to a lesser extent, south Wales. Adults are most likely to be seen in August and September.

Updated, Feb.25 (v.3)