Jane 1, 1S71. ] 



JOUENAL OF HO;<TICULTDKE AND COTTAGE GAEDENEB. 



385 



oases collecting and saving the water in reservoirs would be 

 mnoh more economical than deep-well-sinking, and the water 

 will generally be soft and pure. ' 



Many simple modes of storing water may be resorted to, as 

 a natural pond with grassy sides, a clay-puddled pond, &a., but 

 nothing beats brick and cement. We are sorry that accounts 

 of failures reach us, and we are not surprised, as the work is 

 ■often carelessly done. We have little preference, but we 

 would prefer good Eoman to Portland cement. Then the sand 

 used should be limited in quantity, very clean washed, and sharp. 

 The bricks should be laid in the cement as well as plastered 

 over when laid. Very little cement should be moistened at a 

 time. It will not wait like mortar. Lastly, only good bricks 

 should be used, and they ought to be thoroughly soaked, so 

 that no air-opening may be left before they are laid in the 

 cement. Where air can go water will go. Dryish bricks, and 

 inferior cement mixed with muddy sand, are the chief causes 

 why some brick tanks do not hold water much better than a 

 mud hole. 



Some time ago a gentleman was to show his friends all about 

 ■tank-building. He built his walls 9 inches thick in first-rate 

 mortar, and had 9 inches of clay puddled outside the bricks, 

 and then when finished he had the joints inside raked a little, 

 damped the bricks, and covered with about a quarter of an 

 •inch of cement. The cement cracked, and then the bricks 

 acted as so many sponges to let the water escape. Except after 

 a heavy rain the tank holds little water. 



As regards covered tanks, the form in which the walls are 

 ijuilt matters but little — the circular is the strongest, only if 

 very large, whether square or circular, they would be better of 

 an open wall or arch across. Were we in future building them 

 ■of a large size to be left open, as a reservoir, we would slope 

 the walls outwards instead of building them perpendicular. 

 Wet and frost in the' neighbouring ground have then less influ- 

 ence on the walls. Heavy clay round such walls tries them 

 more than any other soil by expanding and contracting. For all 

 gardening purposes commend us to an open tank instead of 

 any well water. Cement tanks, when shut up from air, will 

 Iiave a tendency for a long time to make the water hard. For 

 Bome years after building it is well to protect the walls of open 

 tanks a little in winter. Wheat straw laid on so as to hang 

 over the wall a foot or 18 inches, fastened with poles laid across 

 the other ends, will generally be sufficient. Evergreen boughs 

 would also serve the same purpose. In severe frost it is ad- 

 visable to break the ice to lessen the expansive force against 

 ■the walls. It is well also to draw enough of water so as to 

 leave a space between the ice and the water. This lessens the 

 •expansion and keeps the body of water warmer. These may 

 seem very trifling matters, but the neglect of them has injured 

 ■many a brick-andcement tank the first winter. The earlier 

 such tanks are built in summer the better generally they will 

 stand. — E. F. 



SOME PREDATORY INSECTS OF OUR 

 GARDENS.— No. 9. 



Somebody tells a story about a traveller who, when he entered 

 an hotel and was about to inscribe his name in the visitors' 

 book, started back in horror and took his departure at once 

 when he observed a certain insect which I need not name walk- 

 ing over the pages. " He had been bitten before," as he ob- 

 served to a friend, " and had taken it patiently, but this was 

 too much. It was the first hotel he had been at where they 

 ■came down to see where you were going to take up your quar- 

 ters !" Whether some mysterious intelligence is conveyed to the 

 realms of the insect world concerning what is printed in this 

 Journal and who writes there I do not exactly know, but it looks 

 at the present time very much as if Abraxas grossulariata was 

 revenging itself upon the author of "Some Predatory Insects, 

 ■&a.," and changing his plural into a singular to make it have 

 a personal interest. In truth, the caterpillars of this moth 

 have abounded within my rather limited domain to an extent 

 ■anparallelled in my experience hitherto, though now reduced 

 by some hundreds through diligent hand-picking. So, good 

 ■reader, if you are ever tempted to attack insects in print, have 

 a caution that they do not retaliate upon you in a rather un- 

 pleasant way. I may add, that having occasion to visit a friend 

 in Surrey, I find that though he is resident only three miles 

 oft from my garden plot, he has on his bushes scarcely any of 

 the caterpillars of tiiis moth, showing that the species is not 

 so prolific generally this season. 



We saw in April the first appearance of butterflies in the 



form of the well-known Garden White ; now its larger and 

 stronger-winged relative, the Large or Cabbage White (Pieris 

 Brassica) is beginning to emerge from its winter tarry in the 

 chrysalis state, and disport itself about the gardens, to the 

 delight of youngsters and the disgust of the horticulturist. The 

 females in particular are soon ready to deposit eggs, which are 

 usually placed in patches of from half a dozen to a dozen. 

 These are placed almost invariably up an some one or other 

 of the cultivated varieties of Cabbage, and, as they are fastened 

 by the base, when we look at them with a hand-magnifier they 

 resemble miniature ninepins. Another author thinks them 

 like an Indian tom-tom, and a stronger magnifying power will 

 show that they are not only ribbed, but marked with delicate 

 lines. These adhere pretty firmly to the leaf, and it is well 

 worth the gardener's while to devote a little time to search- 

 ing after them, not so much to admire them as to prevent all 

 possibility of their producing caterpillars. 



On the wing the perfect insects of Pieris Brassicaj seem in 

 some positions to show a yellowish tinge from the circumstance 

 that the under side of the hind wings is yellowish white ; but 

 there is not sufficient of that colour to warrant the comparison 

 which some think gave rise to the designation " butterfly " as 

 a general term for such insects. The most notably yellow 

 species, the Brimstone, is rarely seen in sufficient abundance 

 about gardens to attract particular notice. Others will have it 

 that the name was given to these "children of the sun" be- 

 cause they are about in most profusion jast at the season when 

 butter is obtained in the greatest quantity. But I must ac- 

 knowledge that neither of these explanations seems to me 

 satisfactory, yet I cannot offer any other. The spring brood 

 of Pieris BrassiciE was at one time thought to constitute a 

 different species, the tips of the fore wings being usually lighter 

 than are those of the second brood which, according to tempe- 

 rature, comes forth in July or August. I have fancied, also, 

 that the early individuals are more lively on the wing than the 

 butterfiies which have to endure the fervid heats of summer. 

 In some seasons there are more successions of the species ; for 

 instance, in the remarkable year 1868 the butterfiies were out ■ 

 almost uninterruptedly till quite late in autumn, and the cater- 

 pillars swarmed on the garden Nasturtium in October and 

 November. Indeed, up to November 15th they were feeding, 

 and some quite small ; after that I lost sight of them. This 

 would lend some support to the statement that caterpillars as 

 well as chrysalids are occasionally to be found in the winter. 

 It is rarely that these caterpillars touch plants which do not 

 belong to the Cruciferous order, though I have seen a party of 

 them experimenting on the Hawthorn by way of change. One 

 of the notable peculiarities of Pieris Brassicas while a caterpillar 

 is its cleverness in finding its way back again to its food-plant 

 when dislodged from it. Bending in a sort of half for a minute 

 or two, it is soon crawling rapidly, and seldom fails in directing 

 its course to very nearly the same spot where it was feeding. 

 When young the caterpillars are often not distinguished from 

 those of Pieris Eapje by the gardener ; when older the superior 

 size establishes the difference, as well as the three distinct 

 stripes and the numerous dark markings. 



The fact is now well established that migrations of this but- 

 terfly take place in some years, accounting for the sudden ap- 

 pearance of swarms of the caterpillars in places not previously 

 infested by them ; and it can even venture across the ocean, as 

 in the instance noted by Mr. Thorncroft, corroborating other 

 instances which had rather been doubted. Mr. Thorncroft 

 says that being on the coast one day in the afternoon, there 

 came in a troop of Pieris Brassicas mingled with Eipss. " There 

 must have been hundreds within a very short space of time ; 

 but what surprised us most was their alighting or settling on 

 the sea with expanded wings, and the ease with which they rose 

 again. They all came in direct from the sea from a south- 

 westerly direction." 



The caterpillars of P. Brassica;, though not like the perfect 

 insects at all inclined to locomotion, do sometimes under the 

 pressure of hunger wander in parties in search of " fresh fields 

 and pastures new." In the Isle of Wight some years ago, an 

 entomologist reports that they spread themselves from the 

 district where they flrst appeared over the adjacent country, 

 crawling in companies over roads and paths, and even climbing 

 over garden walls. On the Cabbages and Broccoli nothing re- 

 mained but stems and fibres. No doubt the excessive multi- 

 plication noticed in some years is favoured by the absence or 

 diminution of the parasitic enemies, which do more than man 

 can effect to keep down the species. Especially are the labours 

 of the ichneumon fly (Microgaster glomeratus) deserving of our 



