Insect architecture / [Anon].

  • Rennie, James, 1787-1867.
Date:
1830
Catalogue details

Licence: Public Domain Mark

Credit: Insect architecture / [Anon]. Source: Wellcome Collection.

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    consider them as such, and predict that they formed the nidus of some species of insects. In more instances than one we have felt so strongly assured of this, that we have kept several specimens for some months, in nurse-boxes, expecting that in due time the perfect insects would be disclosed. One of these pseudo-galls occurs on the common bramble (Rubus fruticosus), and bears some resem- blance to thebedeguarofthe rose when old and changed by weather. It clusters round the branches in the form of irregular granules, about the size of a pea, very much crowded, the whole excrescence being rather larger than a walnut. We expected to find this excrescence full of grubs, and were much surprised to discover, upon dissection, that it was only a dis- eased growth of the plant, caused (it might be) by the puncture of an insect, but not for the purpose of a nidus or habitation*. Another sort of excrescence is not uncommon on the terminal shoots of the hawthorn. This is in general irregularly oblong, and the bark which covers it is of an iron colour, similar to the scoriae of a black- smith’s forge. When dissected, we find no traces of insects, but a hard, ligneous, and rather porous tex- ture. It is not improbable that this excrescence may originate in the natural growth of a shoot being checked by the punctures of aphides, or of those grubs which we have described (page 389). Many of those excrescences, however, are probably altogether unconnected with insects, and are simply hypertrophic diseases, produced by too much nourish- ment, like the wens produced on animals. Instances of this may be seen at the roots of the holyhock (Althea rosea) of three or four years’ standing; on the stems of the elm and other trees, immediately