142 



NA TURE 



[June 



Till Mr. Michael traced the life-histories of these crea- 

 tures, the immature stages of eight species only were 

 known to us. Nicolet, indeed, gives eleven, but as to 

 three he is, in Mr. Michael's opinion, certainly in error. 

 In all other species the life-history when known has been 

 traced by Mr. Michael himself. 



In breeding Mr. Michael used glass cells "composed of 

 ordinary microscopical glass slips 3 X 1 inch, having in 

 the centre, fastened by marine glue or Canada balsam, a 

 glass ring made of a transverse slice of glass tubing aboul 

 § or £ inch in diameter, the length of the tube, and 

 consequently the depth of the cells, being usually about 

 ^ inch. The tubing I employ is of tolerably thin glass, 

 if very thick it is opaque, and leaves little room inside 

 the cell. Over this a thin glass cover, rather larger than 

 the diameter of the tubing, was laid, either a circle or a 

 square ; the latter is often handy, as the projecting corners 

 are convenient to take it on or off by, or sometimes a 

 second slide or a broken piece of one is more serviceable: 

 This cover was always quite loose, and simply held on by 

 an ordinary brass-wire microscopical spring-clip ; of 

 course the upper edge of the slice of glass tube required 

 to be smooth, so that the cover would lie flat upon it, and 

 not allow the minute prisoners to escape. A cell so pre- 

 pared was carefully cleaned out, and examined under the 

 microscope, to see that it did not contain Acarina or ova. 

 A small piece of thick white blotting-paper, not large 

 enough to cover the whole bottom of the cell, was then 

 placed in it and damped ; a piece or two of growing moss 

 or fungus was then placed in the cell, having first been 

 carefully examined under the microscope to see that it 

 also was free from Acarina and ova, and the cell was then 

 ready for use. One or two specimens of the larva, nymph, 

 or species to be observed, were placed in the cell, never 

 so many but what I knew each individual specimen ; the 

 cover was put on, fixed with the clip ; a label with a state- 

 ment of what was inside affixed to the slip, and the whole 

 put away in the dark or very dull light." 



Another good mode of providing the fungus-eating 

 species with food Mr. Michael found to be by putting a 

 minute piece of mouldy cheese in the cell ; this soon bore 

 a fine crop, which was highly appreciated. He found 

 these simple cells answer better than any more elaborate 

 apparatus. Mr. Macintyrc's ingenious cork cells, so useful 

 for many small insects, are not suitable for Oribatidae, in 

 the first place because many are wood-borers, and even 

 those which are not often get lost in the interspaces of 

 the cork. Me also found that these cells got dry more 

 rapidly. 



He tells us indeed (and having had some experience in 

 similar observations I doubt not that it is so) that no por- 

 tion of his work has been either more laborious or more 

 interesting than that of tracing the life-histories of the 

 different species through their immature stages. The 

 creatures are minute, scarcely visible indeed to the naked 

 eye, they avoid the light and always endeavour to hide 

 themselves, and yet they must be frequently examined to 

 see what is going on. They must not be touched with 

 any hard instrument, and lastly their transformations last 

 for many months, sometimes for more than a year. 



It is obvious indeed that his observations required great 

 and constant care. The hygrometric condition of the cell 

 required continued watching, since if it were made too 



damp or allowed to get too dry, even for an hour, the 

 labour of months would be lost. Mr. Michael carried his 

 mites about with him on any journey, but it is obvious 

 that alone he would have been wholly unable to devote 

 sufficient time to the care of them, and it was, he tells us, 

 mainly to his wife's patient attention and skilled fingers 

 that his success in rearing them was due. To Mrs. 

 Michael then, as well as to her husband, we will tender 

 our warm thanks and congratulations on this excellent 

 contribution to the natural history of the British Isles. 



John Lubbock 



INJURIOUS INSECTS 

 Rii> irts of Observations of Injurious Insects and Common 

 Crop Pests during flic Year 1SS3 ; -a'itli Methods of 

 Preservation and Remedy. By Eleanor A. Ormerod, 

 F.R.Met.Soc, &c. Pp. I-So and 1-16. (London: 

 Simpkin, Marshall, and Co., 1884.) 



WE have to congratulate Miss Ormerod on having 

 again produced an excellent summary of the evil 

 doings of injurious insects in this country during the past 

 year. It is full of interesting and useful information, from 

 personal observation, and from the reports sent in by the 

 staff of assistants she has enlisted into her service. Re- 

 garded from a popular point of view these annual Reports 

 do great service by explaining to those interested the real 

 nature of their insect foes ; from a scientific point of view 

 they may do good service by stimulating inquiry, and 

 occasionally bringing to light the hitherto unknown life- 

 histories of certain species ; and they should do para- 

 mount service from an economical point of view. This 

 latter is really the most important of all, and the 

 item of expense in application of remedies is always 

 a serious consideration. With some crops it may some- 

 times be doubtful if the outlay would be sufficiently re- 

 couped ; with others (hops for example) the case 

 different. In that year of hop-famine, 1882, we heard of 

 one grower who expended 15/. an acre on washing, and 

 was amply and abundantly repaid, but if all had done the 

 same his profit would have been much less, though the 

 general advantage would have been much greater : 

 possibly in his case his gardens were comparatively- 

 isolated, and not subject to migrations from those of less 

 careful neighbours. While on this point we observe that 

 Miss Ormerod is inclined to believe in the supposed 

 migration of the hop-aphis from plum to hop. The habit 

 of migration in Aphides from one plant to another totally 

 different is most strongly asserted by Lichtenstein, and 

 almost as strongly pooh-poohed by others. At present 

 we incline to the side of the observant French savant, 

 because he states results from actual observation and 

 experiment, whereas his opponents simply deny the 

 possibility. 



On one point we do not think Miss Ormerod has 

 proved her case. She inclines to the belief that Myriopods 

 (" False wire-worms " as she terms them) are " pests," and 

 do devour healthy vegetable growth ; nothing is impos- 

 sible, but more proof than that given will be required in 

 order to convince those who hold a contrary opinion. 



That much vexed sparrow question is touched upon, 

 not in a manner favourable to the sparrow. It is really a 

 vexed question, and we fear will remain so. * In the 



