Calvia quattuordecimguttata (Linnaeus, 1758)
POLYPHAGA Emery, 1886
CUCUJOIDEA Latreille, 1802
COCCINELLINAE Latreille, 1807
Calvia Mulsant, 1846
A very widely distributed ladybird occurring throughout northern Europe and Asia. In America from Alaska to Labrador and south to New Jersey and California. Our only species of the genus, it is generally common throughout England and Scotland to the very north, including some of the Western Isles, Wight and Anglsey but not from Man, the Orkneys or Shetland. Occurs locally throughout Ireland. They are often found alongside Halyzia. Both adults and larvae feed on various soft-bodied insects and studies have demonstrated a preference for the following species:
Aspen leaf aphid, Chaitophorus tremulae Koch, 1854. Palaearctic, Nearctic and North African species.
Angelica aphid, Cavariella konoi Takahashi, 1939. Holarctic species.
Small willow aphid, Aphis farinose J.F. Gmelin, 1790. European, American and Canadian species.
Black bean aphid, Aphis fabae Scopoli, 1763. Palaearctic, Nearctic, North Africa and South America; one of the most widely distributed species.
Lime tree aphid, Eucallipterus tilliae Linnaeus, 1758. Native to Eurasia but now much more widely distributed.
Birch aphid, Euceraphis betulae (Koch, 1855). Europaean endemic, now much more widely distributed.
Mugwort aphid, Macrosiphonella artemisiae Fonscolombe, 1841. Palaearctic, Nearctic and African species.
In the U.K. Calvia overwinters in the adult stage among hedges, bark, beech mast and leaf litter etc. and at this time they can often be sieved. From April they may be beaten from various deciduous trees; ash and lime seem to be preferred but they occur on a wide range. Locally, in Cassiobury Park, they are common most years on copper beech. Typical habitat is woodland or wooded parkland but in some years they are common in gardens etc and we have attracted them to U.V. light.
Calvia 14-guttata 1
Calvia 14-guttata 2
Calvia 14-guttata 3
Calvia 14-guttata 4
Calvia is one of the most effective entomophages of pests of a range of fruits and trees. It is found in apple and pear orchards, in deciduous and mixed forests, parks, and forested zones on elm, ash, alder, maple, oak, birch and bird-cherry. The beetles overwinter in forest litter near the base of trees as well as on the fringe of deciduous and coniferous forests. Adults become active in mid-April when they are known to feed on overwintering eggs of psyllids. Oviposition usually coincides with the emergence of nymphs of various psyllids. Eggs are only laid on trees infested with psyllids or aphids, on stems, small twigs and branches , in crevices or cracks etc., generally below 4 metres but sometimes higher (on elm.) The small eggs are characteristic; yellowish white with two large bright orange spots, a smaller one and many minute spots. They are arranged in more or less regular rows. After overwintering and during oviposition the ladybirds feed voraciously, each consumes up to 50 small psyllids a day. Each female may lay more than 300 eggs. The larvae may roam several metres searching for psyllids and aphids etc. and development is rapid; they are fully developed within 2 or 3 weeks. Pupation occurs in crevices or twisted leaves, only very rarely exposed. After the wings have developed young beetles can feed on a wide variety of aphids etc. if psyllids are not available. Calvia begins overwintering slightly earlier than other coccinellid species, at the end of July or the beginning of August. The life cycles of Calvia and various psyllid species has ben shown to be synchronized; in the absence of adverse effects e.g. parasitism or competition it has been established that if Calvia start developing simultaneously with the emergence of psyllids from eggs and feed on the young nymphs, then each Calvia can consume 200-400 psyllids. The role of Calvia in increasing yield in orchard environments is therefore important.
Without experience of ladybirds Calvia be mistaken for Halyzia in the field but it is usually darker and the arrangement of spots is distinctive; spot fusion is rare and there is very little variation in Calvia, other than in the ground colour. There is a rare melanic form, nigripennis.
<6.5mm. Elongate oval and very convex. Entirely orange, brown or maroon but for the pale markings which are often edged darker. Head with coarse puncturation and very fine microsculpture. Clypeus narrowed in front of eyes exposing the antennal insertions. Tips of antennae and palps darkened. Antennae long and slender and with a well demarked 3-segmented club, the last segment of which is truncate or concave at apex. Mandibles bidentate at apex. Front margin of eyes sinuate and notched in front of antennal insertions. Pronotum transverse, surface punctured and shiny, without microsculpture. Widest behind middle, with margins explanate. Front angles produced forward. Scutellum triangular and finely punctured. Each elytron with 7 pale spots, 3 of these form a transverse band on the front half. Surface shiny, without microsculpture. Margin explanate behind shoulder and narrowing to apex. Underside orange but for pale meso- and metepimera. Front margins of meso- and metasternum strongly notched and bordered. Front margin (only) of first abdominal segment lacking a raised border. Claws strongly angled at base and with a well-developed basal tooth or lobe.
Calvia Mulsant, 1846
A small genus of around 20, species primarily from the Palaearctic and Oriental regions and with several endemic to the Himalayas. There is a single species in the U.S.A., C. quattuordecimguttata (Linnaeus, 1758), and 3 species are widespread in Europe: C. decemguttata (L.), C. quattuordecimguttata (L.) and C. quinquedecemguttata (F.) They are comparatively large ladybirds, up to 7mm., colourful and insectivorous across a wide range of hosts, mostly broad leaved trees but also shrubs and herbaceous plants that are hosting a sufficient population of aphids or psyllids etc. The eggs of C. quattourdecimguttata appear to be chemically protected from attack by the larvae of the Harlequin ladybird, most coccinellid eggs are consumed but Calvia eggs are almost always avoided. All species share the following characters:
Anterior pronotal angles produced.
Lateral margins of pronotum and elytra explanate.
Mid- and hind-tibiae each with a pair of spines at apex.
Abdominal postcoxal line incomplete.
Tarsal claws appendiculate.
Calvia decemguttata (L.) has occurred several times in the U.K. and may do so again due to climate change. This is a common north-western species on the continent; slightly larger than C. quattuordecimguttata (L.) on average and with 5 pale marks on each elytron but otherwise broadly similar to our own species.