|Sitona hispidulus (Fabricius, 1777)|
|A common and often abundant species throughout England and Wales, less so
throughout Scotland and so far not recorded from the Hebrides, Orkney or Shetland (Morris, 1990). In 1922
Dorothy Jackson produced a fine paper detailing much of the species life history and most of what follows is summarised
from that work. Both adults and larvae feed upon, and have occasionally been pests of, clovers (Trifolium spp.),
lucerne (Medicago sativa) and , more rarely, may be found on peas. Typical habitats are permanent arable pasture,
wasteland, untended gardens and roadsides and scrubland where the foodplants abound. Adults feed on the leaves and are
usually present in small numbers, damage rarely being serious. Feeding proceeds from the leaf edge and continues
between veins, specimens often return to enlarge the same area of damage so that characteristic, irregular U-shaped
notches result. Although there is a single generation each year, the adults are long-lived, typically 12 months and so
may be found year round, the new generation emerge from pupae between July and September. Egg laying begins from six
to eight weeks after the adults emerge. Eggs laid in the autumn mostly overwinter, any larvae hatching at this time do not survive.
Adults are abundant during the autumn and become adventitious, they may be found on walls etc and often in numbers,
both macropterous and micropterous forms occur and both display this adventitious behaviour. Adults remain active
an continue to feed through the winter, they may be found under feshly attacked clover plants during periods of frost.
During the first warm spring days they may be found walking among or below the foodplant, at this time they are also
nocturnal. Egg laying recommences at this time and is prolonged, continuing into July, so that the progeny from an
individual female may be present at various stages of development. Eggs are laid indiscriminately, wherever the adult happens to be
resting, generally between tow and five are laid each day but higher numbers have been recorded and they hatch
within three to five weeks. Autumn larvae invariably do not survive, the winter being passed in the egg or adult stage.
Larvae occur from the end of April until August, taking between eleven and fourteen weeks to develop. Larvae on the roots
of the foodplant, boring deep holes all over although that part of the root just below the crown is often attacked causing
the shoots above to die; in larger plants the outer shoots die while in smaller ones the root may be completely
bitten through. Larvae are most abundant during June and July. Pupation generally lasts between three and four weeks
and new generation adults appear from August into late summer.
This species occurs throughout the Watford area and may be found, usually as individuals or in small numbers, by sweeping suitable habitats; Common moor is usually a reliable source.
The parallel form and short robust rostrum make Sitona species distinctive in the field and with a little experience hispidulus is usually obvious with a X10 lens.
2.8-4.6mm. Entire upper surface with recumbent round to somewhat elongate metallic golden, coppery to green scales, these are usually rubbed to some extent exposing the shining black cuticle. Entire surface of head with small semi-erect scales among the more dense recumbent scaling, cuticle betwen eyes flat with a short longitudinal impression. Eyes very weakly convex, hardly protruding. Rostrum short and broad, almost quadrate - measure from front of eyes, with an impressed line by antennal insertions, often indistinct. Scrobes not visible from above, bent down and widened to in front of eyes. Antennal insertions hidden by upper edge of scrobes. Scape shorter than head between eyes, bent at base and clavate. Pronotum evenly rounded laterally, entire surface with large punctures which are visible among the scales. Generally with three lines of lighter scales and with semi-erect forwardly directed curved scales, these are much shorter than the erect elytral scales. Scutellum with dense recumbent scaling. Elytra parallel with prominent shoulders, all interstices weakly convex at base, otherwise flat. Striae coarsely punctate. Each elytron with 9 distinct longitudinal rows of erect, curved setae-like scales. Legs red with femora darker, at least basally. Femora without teeth. Protibiae in male more strongly toothed and incurved apically. Claws free.
Description from 1 Watford species at X20
Jackson, D.J. 1922. Bionomics of weevils of the genus Sitona injurious to leguminous crps in Britain. Part II Ann.Appl.Biol. 9:93-115.