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The Pamphlet Collection of Sir Robert Stout: Volume 14

The Hop Cone-Strig Miner (Psylliodes attenuatus; or Agromyza frontalis?)

The Hop Cone-Strig Miner (Psylliodes attenuatus; or Agromyza frontalis?).

During the last few years the hop cones in many parts of the hop-yielding districts have become rapidly red or rust-coloured some days before they were ready to be picked, and after a short time they have dried up, and their bracts have fallen to pieces. This was at first attributed to red mould or to red rust, but upon careful examination it has been found that the strigs or stalks of the cones had been bored or mined by an insect throughout. Moreover, in many of these mines little white maggots, the larvae of an insect, were found.

It is a moot point as to what kind of insect these larvæ belong. Some are of opinion that they are the larvae of a species of flea-beetle, of the tribe Psylliodes, either Psylliodes attenuates or Psylliodes chrysocephalus, which, to a casual observer, resembles the common hop flea beetle, Haltica concinna. According to Taschenberg the larvæ of the latter commonly bore into bulbs or stalks of plants. Others hold that they are the larvæ of a species of fly, Agromyza frontalis, which are also known to be leaf and stalk miners. Miss Ormerod reports of some larvae forwarded to her, together with the injured strigs of hop cones, that they decidedly were those of a dipterous insect, that is, of some two-winged fly. Miss Ormerod kept these larvæ, hoping to witness their transformation, but unfortunately they lost their vitality.

It is hoped that planters will send specimens of these to Miss Ormerod or to the writer, in order that they may be identified, and that means of prevention and remedies against their attacks may be prescribed, as the injuries caused by them are serious, and are, as it appears, on the increase.

C. W.

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London: Printed by Eyre and Spottiswoode, Printers to the Queen's most Excellent Majesty.