File:The American entomologist (1868) (17932990089).jpg

Title: The American entomologist
Identifier: americanent1218681870stlo (find matches)
Year: 1868 (1860s)
Authors:
Subjects: Entomology
Publisher: St. Louis : R. P. Studley & Co.
Contributing Library: Smithsonian Libraries
Digitizing Sponsor: Biodiversity Heritage Library

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156 THE AMERICAN ENTOMOLOGIST. this genus (Decatoma), bred from the above galls and now in the collection of the Senior Editor, is 217. Those that require further in- formation on this somewhat dry subject are referred to the forthcoming Scientific Article by the Senior Editor, in which will be found de- scriptions of about a dozen new species belong- ing to these two parasitic genera (Eurytoma and Decatoma). We will now give lateral or profile views of the same Joint-worm Fly, the female of which has been drawn as viewed from above in Figure 113, b. Compare these profile views with those (Fig. ai7.)
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Color—Black, of the two true parasitic genera (Eurytoma and Decatoma) given in figures 115 and 116, and it will be seen at once, even by the unscientific rea- der, that the last insect is totally unlike either of the two first, and manifestly can not be referred to the same genus. Not to dwell upon structu- ral minutife which willbe explained elsewhere, it will be seen at once that in the Joint-worm Fly (Fig. 117, a § , 6(3') the abdomen in both sexes, but especially in the female, is shaped quite dif- ferently from that of either of the two parasitic genera (Figs. 115 and 116), and that the body is nearly straight in repose, instead of being curled into a semicircle as in the two first genera. This latter peculiarity is not a mere fortuitous circumstance, happening to particu- lar individuals, but is universal in all specimens belonging to the two genera first figured (Eury- toma and Decatoma); so that it is with great difliculty that their bodies can be sufficiently straightened out in death, to admit of their being mounted upon card in the comparatively straight posture shown in the figures (115 and IIC), their heads being usually found stifliy doubled up downwards upon their tails. Even in life, they frequently assume this posture, when they wish to "play opossum" and escape the attention of the observer. On the other hand, the Joint-worm Fly has no such peculi- arity either in life or in death, or at all events but to a very limited extent. A very curious chapter might be written on the difierent modes in which different insects— upon the same principle as that just now ex- plained—form themselves into the similitude of a round ball-like seed or pellet of dung, and thereby escape the attention of their enemies. To refer to but a few of such cases: Among the Beetles, one genus (Byrrhus) has separate cavities on the lower surface of its plump oval body to receive each leg, the leg doubling up and fitting into the cavity as smoothly, as does each particle of the finest piece of mosaic work into its appropriate position. In other genera (Agathidium, Leiodes, Clambus and Sphwro- morphus)the body itself is rolled up downwards, head and tail together, into a more or less com- plete and smooth ball. In the well known Cur- culio (Conotrachelus nenuphar, Herbst) and many other Snout-beetles, the beak in repose is laid along the breast between the front legs, certain genera having a deep groove there to receive it; and the legs being then crumpled up close to the body, the whole creature looks exactly like the dead bud of a tree. In other gen- era of beetles (Clilamys and Exema), belonging to the same great Family (Chrysomela) as the Colorado Potato Bug, the whole upper surface of the body is rough, dai-k-colored aud opaque; and when the legs are retracted, even good ento- mologists have been often deceived into mistak- ing the insect for a pellet of dung voided by some large caterpillar. Lastly, among the Golden-tail Flies (Chrysis family) in the Order Hymenoptera, all the genera, when threatened with danger, roll themselves up head and tail together, leaving their wings exposed. In this case, as indeed in all other such cases hitherto recorded in any Order of Insects, the little creature curls itself up downwards, and the back forms the convex aud the breast the concave side of the ball into which it contracts itself. The same thing holds good with certain genera of Sow-bugs (Oniscus family) belonging to the Crustaceans, which roll themselves up into a more or less complete ball. But there is a re- markable and hitherto undescribed genus of Chalets flies, a single species of which (^Anti- gaster mirabilis, n. sp.) exists in the Cabinet of the Senior Editor, and which will be found figured below, 1st iu Figure 118, fl, as viewed from above with the wings and legs expanded, 2nd in Figure 118, b, in profile when preparing to curl up, and 3rd in Figure 118, c, in profile,

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