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Hawthorn Jewel Beetle Agrilus sinuatus

Hawthorn Jewel Beetle. One of Philip Harwood's specimens photographed at Oxford University Museum of Natural History.

I have never actually seen a live Hawthorn Jewel Beetle Agrilus sinuatus though I have recorded the species on a dozen occasions. It can be found over a wide area of southern England (map here) by looking at mature hawthorns where the D-shaped exit-holes are a tell-tale sign. The D-shape matches the cross-section of the adult jewel beetle: flattened on top and convex below. The holes are best looked for on lower branches that are dying back but can also be found on the trunk and major boughs.

D-shaped exit hole characteristic of Agrilus.

To be extra sure you have found Agrilus sinuatus exit-holes, you can whittle away the bark to reveal the vacated larval borings which seem to always have quite a regular snaky, zig-zag pattern. The larval borings are also illustrated in a note by Keith Alexander (1990) who pioneered the recording of jewel beetles in this way: available online here. I would like to think that the ‘sinuatus’ of the name (given by Olivier in 1790) refers to the sinuate pattern of the larval borings.

Snaky borings of Agrilus sinuatus in a hawthorn branch.

Finding adults in the field must require some luck. They may be very short-lived, they may spend their lives out of reach around the crowns of hawthorns, or they may be too flighty to simply tap them out onto a beating tray. Agrilus sinuatus was regarded as ‘very rare’ by Fowler in 1890, as Vulnerable (RDB2) in 1987, and was downgraded to Nationally Scarce (Na) in 1992 and although still officially Na today we can probably safely call it common, largely thanks to a better understanding of how to spot the signs.

The best way to see adults would presumably be to rear them out of a suitable hawthorn branch. Under natural conditions, adults are active from mid-June to late September so collecting a branch any time up to mid-June ought to do it. The trick would be to find a branch that doesn’t yet have any D-shaped holes in it but looks like it will do soon!

Reference

Alexander, K.N.A. (1990). Agrilus sinuatus (Olivier) (Coleoptera: Buprestidae) widespread in Gloucestershire, and at a Herefordshire locality. British journal of entomology and natural history, 3: 31 – 32. [Browse this article online here].
 


6 Comments

  1. Valerie Kaufmann says:

    I found a live jewel beetle! When digging up my potatoes in November. It is a vivid green with a pinkish copper underside. It was on my allotment in SW London.

  2. markgtelfer says:

    Sounds like a jewel indeed. Funny place to find one!

  3. Adrian dutton says:

    Mark, my technique here in Nottinghamshire to find A. sinuatus is to wait for the hottest day of the year usually end July and beginning of August, then go out and beat every tree with exit holes. So far I have found 4 specimens this way on three separate occasions. Seems to work, or I may have just been lucky.

  4. markgtelfer says:

    Thanks Adrian, I just got Oscar Vorst’s book on Dutch buprestids 2 days ago and it has phenology charts for each species. Looks like June and July are the best months for sinuatus with a steep drop off in August. So your technique might be even more successful earlier in the season.

  5. Martin F. Heyworth says:

    In July 2011, I found what was almost certainly this species (Agrilus sinuatus)on a pavement underneath a species of hawthorn tree in Philadelphia (Pennsylvania, USA). I did send Keith Alexander an e-mail about this. The specimen was not photographed, and was not added to a collection, so this is – at best – a verbal record. Presumably, Agrilus sinuatus is one of several European beetles introduced to North America at an unspecified prior time.

    Parenthetically, Trachys minutus is (or, at least, was) locally common at a site in Oxfordshire in 1979-1980 (as mentioned in a short note that I published in the Entomologist’s Monthly Magazine in 1994).

    Another verbal record is of a green Anthaxia (possibly A. nitidula) that I found on hawkbit-type flowers in the Montpellier Botanic Garden (southern France) in July 1987.

  6. markgtelfer says:

    Thanks for the records Martin.

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