594 



NA TURE 



[August 24, 1803 



The Gardens of the Hairy Ants. 



While working at the preceding it was discovered that 

 somewhat similar fungus gardens occur in the nests of 

 Apterostigma. Four species were studied. All have the 

 same fungus, belonging apparently, however, to a 

 different genus from Rozites. These hairy ants live in 

 decaying wood and have small gardens 4-8 cm. in dia- 

 meter, built of bits of wood-fibre, beetle-dung, &c. The 

 chief point of interest is that though all have the same 

 fungus yet all have not cultivated and selected the Kohl- 

 rabi to the same degree. A. Wasinanni, Forel, has a 

 well-developed type with large spherical swellings on the 

 ends ofihe hypha;. The others have Kohl-rabi of a much 

 lower type, the hypha; being only slightly swollen into a 

 club shape, and they are not aggregated into regular 

 groups. 



It was, as usual, found impossible to obtain by artificial 

 culture the highest fructification of the fungus, so its 

 systematic position is still undetermined. 



The Gardens of Cyphomyr.mex. 



This genus of ants is closely related to the two preced- 

 ing, and the two species examined (C. auritus, Mayr, and 

 C. sirigatiis, Mayr) are also fungus-growers. Both form 

 nests like those of Apterostigma, and use similar maierial 

 in the garden. The two species have the same fungus, 

 but C. sirigaius obtains far finer Kohl-rabi than C. 

 auritus, just as we have seen to be the case with the 

 species of Apterostigma. It is thus pretty evident that 

 the large size of the best Kohl-rabi must be due to 

 selection and cultivation on the part of the ants. 



The concluding pages of the work are taken up by a 

 discussion of the mycological results of these investiga- 

 tions, for which reference must be made to the original. 

 The work is illustrated by beautifiil plates, and forms as 

 a whole one of the most fascinating contributions to 

 botanical literature that have been made for many years. 



John C. Willis. 



A FEW REMARKS ON INSECT PREVA- 

 LENCE DURING THE SUMMER OF 1893. 

 WJ E are hearing a great deal just now of unusual 

 ^ amount of insect presence, and there appears no 

 reason to doubt that such is very much the case, 

 although for scientific use we need much more of reli- 

 able report than we possess as to what kinds of insects 

 are noticeably more present than in seasons of ordinary 

 meteorological conditions, and also we need observations 

 as to what kinds may be unusually absent. 



So far as my own acquaintance with the subject 

 {which is mainly in reference to amount of presence of 

 ■crop insects) allows me to judge, these unusually large 

 amounts where they occur — for the superabundance does 

 not aftect all kinds — may be attributed to weather 

 influence acting either directly on the development of 

 the insects themselves, or so affecting the state of their 

 crop-food-plants as to induce the conditions which we 

 know well by the agricultural experience of many years 

 are favourable to establishment of infestation. 



The important preliminary as to there having been 

 really such a definite deficiency in rainfall as to amount 

 to what may be called " a drought " over England and 

 Wales, we have stated shortly in the Monthly Meteoro- 

 logical Magazine, of Mr. G. J. Symons, F.R.S., No. 

 cccxxxi , p. 98, as follows : — " Assuming that the twenty- 

 four stations fairly represent England and Wales, we 

 find that in March the rainfall was only one-third of the 

 average, in April one-sixth, in May three-quarters, and 

 in June two-thirds." Mr. Symons further points out 

 that "this, of course, is taking the country as a whole ; 

 at many individual stations the results -would be much 

 more striking, e.g. at Bodmin in the three months •' ( March 

 •to May) "only one fifth of the average fell." 



Amongst insect attacks especially subject to increase 



NO. 1243, VOL. 48] 



by stunting of growth, or over-maturation of sap of ihci, 

 food plants, are those of the Aphides or Plant Lice 

 which have been— so far as my own contributors' repnrti 

 show — unusually early and prevalent this year. The) 

 were forwarded on mangolds from Devonshire almost a 

 soon as there could be said to be good accommodaiior 

 for attack on the leafage, and turnips and cabbage leafage 

 damson early in the season, and larch later on the bor 

 ders of England and Scotland, were some of the tree ant 

 food plant habitats which were exceptionally afflicted 

 These prevalences agree with the rule of Aphis life !ai( 

 down by Mr. G. B. Buckton, F.R.S., our great authority 

 on Aphis life. In drawing attention to the abnormaH; 

 rapid increase of Aphides under some circumstances, hi 

 accounts for it by maturity [i.e. power of reproduction 

 taking place earlier in the life stage where from variou 

 causes inducing want of supply of nutriment, structiira 

 changes occur consequently on these in the larvae of thi 

 Aphides subsequently born. (See " Brit. Aphides," b; 

 G. B. Buckton, FR S., vol. i. p. 72). 



Besides the above reasons for increase, we have ahi 

 the negative reason of absence of destruction by goot 

 drenching rains to wash off and often to drown th 

 enemy. One of my correspondents wrote me that hefaai' 

 been doing this or that, but the best help was the v»d 

 come rain. 



The above may be taken as a type of one way in whic 

 weather influence acts ; in the case of wasps, which popi 

 larly represent much of insect presence to the world s 

 large, we have another set of influences. 



Our recent drought began in March. In many yeai 

 we have the most variable weather at this seam 

 and the queen wasps, the foundresses of the coimn 

 colonies, being tempted from their winter localities 1 

 hybernation by a day or two's warmth, are caught, itww 

 be, by heavy rain, or by snow, or by frost, and perW 

 This year weather was more favourable to then:, and » 

 had not the drenching rains which in an ordinary ye^ 

 put an end to many an embryo nest with its few grub 

 whether in ground or hedge. The first commencemer 

 formed of a tiny piece of paper, in shape like an nn 

 brella, with beneath it a pendant ending in a club forme 

 of a few cells, each with its ^%z or young maggot tenar 

 is delicate in the extreme. If the cavity in which it 

 placed in the ground is flooded, its destruction is certai 

 or if in storms the foundress cannot return to feed tl 

 young family they must perish. 



In the case of wasps, probably weather iufliwnce 

 which affect amount of any particular kind of food are ,1 

 little troublesome as to any insect. All who at all stu' 

 their habits are aware that flesh, fish, insects to a lari 

 amount, and fruit to utter rapacity of consumption, n 

 constantly utilised by them for their own special suppc 

 or that ol the maggot family. To what extent the adi 

 wasps may feed on other than vegetable matter I canti 

 say, but dissection and examination of the undigesn 

 food in the blind pouch of the food canal of the Ian 

 wasp has shown this to consist of remains both of anin- 

 and vegetable matter ; in the record before me chiefly 

 insect lit'bris. Their varied kind of food and their f'-' 

 derful adaptability of instinct in making adverse c 

 cumstances suitable for the househjld need?, make t 

 wasp family when once established, most prolific pests 

 The great prevalence of what are called surface cat' 

 pillars, that is, the larva; of various kinds of Agrotis 

 the roots of various kinds of field crops, gives an exam| 

 of increase of presence of the Lepidoptera, under circu 

 stances favourable to the development of the imago fn 

 the chrysalis, and subsequently to the pairing Of j 

 moths and successful egg deposit. In wet and d 

 weather, when the moths hang about torpidly, a cert, 

 proportion of them get drenched, so that their wings ;;• 

 of little service ; the larv;e are injured in different wa , 

 or disease induced, much influencing amount of prescn: 



