AprU 20, 1S71. ] 



JOURNAL OF HORTXOULTUKB AND COTTAGE GAKDENEE. 



289 



nature. Would it not be better to draw white flowers on paper 

 tinted by lithography, the white Bpaces occupied by the flowers 

 being left white ? 



SOME PREDATORY INSECTS OF OUR 

 GARDENS.— No. 7. 



It ia an observation almost rnb'oed threadbare to say that an 

 object varies much according to the peealiaritiss of the eyes 

 which contemplate it ; and the only esouse which can be made 

 for its repetition is, that palpable as is the truth of it to most, 

 there are some persons slow to receive the explanation which 

 it affords of certain seeming oontradietions. I was reminded 

 of it now when considering the diverse effects produced in the 

 minds of men by the appearanca of the first butterflies of 

 spring. The poet looks at tbem with rapture, and rushes, with 

 a new inspiration to his desk, to pour forth his thoughts in 

 verse ; the naturalist surveys tbem with interest, and with a 

 degree of pleasure also ; and the gardener, he — why, ho feels 

 inclined to anathematise them as the detestable parents of a 

 prospective brood of devourers, which will ere long make some 

 of his Cabbages and Gaaliflower.s " small by degrees," but 

 not " beautifully less," though as yet a moiety remains of 

 those engaged in horticulture who have not learnt this relation 

 between cause and effect, and who gaze at the white butterflies 

 fluttering in the April sunshine, and do not connect them with 

 the swarming caterpillars of a month later. 



The earliest butterflies we see in the spring are some of 

 those belonging to the Vanessa family ; indeed even in January 

 or in February we may see a Peacock or a Tortoiseehell career- 

 ing about in company with the more uniformly coloured Brim- 

 stone, and looking rather unseasonable. The first species, 

 however, which emerges from the chrysalis is usually the Small 

 or Garden White (Pieris Kipas), which maybe reckoned with 

 good reason amongst the harbingers of spring. That some 

 individua's belonging to this species lived through the winter 

 in the imago or butterfly condition, was the belief of the older 

 entomologists, and it may possibly be sometimes the case, 

 though I have seen no positive proof of it. The overwhelming 

 maj >rity of the specimens we see in April have, at any rate, 

 not long emerged from the chrysalis, as is evident upon an 

 examination of their wings, which have a freshness not observ- 

 able in hybernated butterflies. This circumstance is advan- 

 tageous, as affording an opportunity for their destruction ere 

 they can wing their flight, since the ohrysalida are not concealed 

 — or at least only slightly so — as they are attached to some 

 wall or paling, or, rarely, to the trunk of a tree. Seeking out 

 and destroying these, in the winter or early in spring, in those 

 places where the caterpillars have been observed the preceding 

 summer or autumn, might be reg'jirded as tedious work, yet it 

 would certainly pay in its results in so far as cultivated plants 

 of the Cabbage family were concerned. Probably each female 

 butterfly deposits 1.50 eggs at least ; then the destruction of 

 each hundred in the chrysalis stage might be reckoned as eciui- 

 valent to the extermination of 7500 caterpillars, and though 

 many out of such a number would be destroyed by various 

 causes before they could do much damage, a good per-centage 

 would attain maturity. We are, it must be remarked, rather 

 fortunate in these islands so fir as our butterflies are concerned. 

 We have but a small number of species native with us — a fact 

 which it has been attempted to explain by several theories, 

 none to my thinking at all satisfactory — and of these only two 

 or three are at all injurious to cultivated plants. Certainly the 

 species before us is markedly if not extensively so, the cater- 

 pillars not only feeding on the plant which gives the name to the 

 species, but attacking almost any of the Cruciferas, and showing 

 themselves also most years in our flower gardens to feed upon 

 various aonuals and biennials. In my own domain, I have 

 noticed that Siooks and Mignonette are especially favoured by 

 their presence. 



The eggs of Pieris Eipaa are saffieiently large to be noted by 

 the unassisted eye, resembling those of P. Brassicaa, which 

 have been often figured, only not quite so elongated. They 

 are marked with ribs and also striated, being disposed on the 

 leaves ia patches of half-dozons or dozens. The first proceed- 

 ing of the newly hatched ciiterpillars is generally the devouring 

 of the empty egg-shells — in act of apparent indiscretion, we 

 might say, as it seems likely that so hard a substance would 

 not suit very well the delicate digestive apparatus at that stage ; 

 however, the successful growth subsequently proves that the 

 act is by no means suicidal. The spring brood of larvaj appear 

 within a fortnight after the eggs are laid, the primary object 



of their attack being very often the varieties of Cauliflower and 

 early Cibbage, they being at first hardly noticed from their 

 small size and pale colour. Newman describes, with his usual 

 accuracy, the appearance of these caterpillars until the second 

 change of skin. " They are semi-transparent, the hairs con- 

 spicuous, and each has a spherical head like a pin ; indeed, 

 they much resemble so many minute pins stuck into the skin, 

 or, still more exactly, those minute stalked glands which are 

 commonly observed in the stalks of Ferns and other plants, 

 There are a number of white warts on each segment." The 

 rate at which these caterpillars grow depends greatly upon the 

 temperature, easterly wiads and heavy rains retarding their 

 progress, and even killing a considerable number. With favour- 

 able weather they proceed very rapidly towards maturity, and, 

 they may be ready to become chrysalides in three weeks' timei 

 from emergence. Attaching themselves at a variety of angles 

 to wooden surfaces not far from where they have fed up, these 

 develope into a second brood of butterflies, which continue on 

 the wing for a rather longer period than the flight we see now. 

 The chrysalis, it may be noted, is of different shades, of white, 

 light and dark brown, and occasionally green, and has been 

 conjectured to be adapted to the particular hue of the object to 

 which it is f-tstened, ao as to favour concealment ; the suppo- 

 sition is hardly sustained by experience, though we have other 

 undoubted instances of insect disguises. No fixed date can be 

 named for the appearance of the second brood of caterpillars, 

 and in some seasons there seems to be a succession of broods, 

 and caterpillars, chrysalides, and butterflies may be found, if 

 not iu the same garden, at least within a distance of a few 

 miles. 



In some years Pieris EapEB is comparatively scarce, it was so 

 in 1869, though ia the preceding remarkably warm summer it 

 abounded in most places ; in fact, that year produced many 

 curious phenomena both in plant and insect life. Thus, there 

 were caterpillars of this species feeding at the west end of 

 London up to the middle of June, which was later than usual 

 for the first brood, the appearance of the butterflies having 

 been retarded by a cold April. Early in July, near GravesenJ, 

 both larva3 and chrysalides were found, and the butterfly was 

 also out. At Fulham, on the 22nd of that month, there were 

 hosts of larvas crawling on the palings to enter the pupa state. 

 0.1 August Isf, in some places about the metropolis, the butter- 

 flies flaw almost in swarms, both in fields and along the road- 

 sides, settling with eagerness in parties of six or eight at any 

 spot where water had been spilt, and allowing the observer to 

 come quite close. Three weeks afterwards they were nearly as 

 numerous as at the commencement of the month, and another 

 arrival of larvae were destroying the parched leaves which yet 

 remained in our gardens, many of them exhibiting signs of the 

 attacks of parasites. On the 10th of Ssptember some half- 

 grown caterpillars were seen feeding. Many butterflies were 

 flying throughout that month and October, individuals which, 

 in the general way, would not have come forth until the spring, 

 accounting for the scarcity which ensued in 1869 ; nor had the 

 species recovered itself even in 1870. 



How is the species we are discussing to be kept under by the 

 gardener ? This admits of several answers. The hunting-ont 

 of the chrysalis is a good plan, as already hinted. Capturing 

 the butterflies by means of a net has been tried, but this in- 

 volves an expenditure of time without producing an equivalent 

 result, nor is it very probable that the eggs will be detected in 

 any quantity just at the right moment. There are some cater- 

 pillars which can readily be shaken off their food plants, but 

 that of P. Rapse holds on pretty firmly. When a greater force 

 ia applied, then they roll into a ring, soon, however, begin- 

 ning to crawl again. Children may be sometimes employed 

 with advantage to pick them off, and the birds if let alone 

 will render the gardener much service. Some caterpillars 

 are destroyed by the same parasite which attacks the caterpil- 

 lars of P. Brassicffi, a larger number still by the maggot of a 

 dipterou?! insect. Eennie, in his interesting volume on " Insect 

 Transformations," states that in his researches iu soma fields 

 at Islington (only fancy, there was actually a man living not 

 long since who had seen fields there !) he had observed that the 

 caterpillars of P. Raps selected in preference the wild brassi- 

 caceous plants, neglecting the cultivated species. With all 

 respect, however, I do not think that this solitary instance 

 suffices to build a theory upon. There may have been iu this 

 case soma means taken to prevent their attacking the Cabbages 

 and Broccoli, otherwise I believe the mild flavour of the culti- 

 vated species proves more to the taste of the caterpillars of 

 P. Eapffi than the harshness of the wild species. 



