BOOK REVIEWS. 



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usually makes a hole, some nine or ten inches in depth, under some 

 fresh dung, into which it thrusts a pellet of dung on which it lays an 

 egg ; when the egg hatches, the young grub finds itself surrounded with 

 fcod. On p. 169 it is said that the perfect mayfly changes its skin soon 

 after it has reached maturity. This is not really the case, as the mayfly 

 does not appear as a perfect insect until it has cast the skin with 

 which it is covered when it emerges from the pupal covering. There is 

 evidently a misprint on p. 181, where a sentence reads : " the larvae or 

 grubs of saw-flies are sometimes called false caterpillars, because a true 

 larva possesses not more than sixteen legs." We presume that the author 

 intended to say " because a true caterpillar possesses not more than 

 sixteen legs." In the account given of gall-flies no allusion is made to 

 the very interesting fact that most of the gall-flies of the oak have to 

 pass through two generations before the life-cycle of the insect is 

 complete ; that is, a gall-fly lays an egg in the bud of an oak, a grub is 

 produced, which forms a gall quite unlike that from which its mother 

 emerged, and this grub, when it eventually becomes a gall-fly, is quite 

 different from its mother in form, exactly resembling its grandmother in 

 appearance, while the grub hatched from its egg forms a gall of the 

 same nature as that of the last generation but one. For instance, the 

 gall-fly that is produced from the " common oak spangle-galls," in 

 the spring lays her eggs in the male blossoms of the oak, and the 

 galls which result are very unlike the spangle-galls, and are known as 

 currant-galls on account of their resemblance to a small bunch of 

 currants ; the flies from these galls lay their eggs on the undersides of 

 the leaves and spangle-galls are formed. 



On p. 188 it is mentioned that it must not be supposed that all gall- 

 flies produce galls, as some of the smaller ones do not, but are parasitic. 

 This requires some explanation, as none of the gall-flies are parasitic in 

 the way of living on some other insect ; but they lay their eggs in the 

 galls already formed by some other gall-fly ; this, however, does not 

 interfere with the maker of the gall. 



Worker-bees are said on p. 211 to " have a brief but busy existence ; 

 so hard do they work, these rightly named worker-bees, that they often 

 die of sheer exhaustion." That they have a brief existence is true ; 

 most insects in their perfect state have a very short life — some species, 

 indeed, only live a few hours — but that they often die from sheer 

 exhaustion is very doubtful ; some probably perish when at work if they 

 are caught in a violent shower, as they would not be able to fly through 

 it, but would get thoroughly wet and be much knocked about, and very 

 likely would be unable to reach their hive. Bees are said to collect 

 propolis from flowers ; this is a mistake. Propolis is a resinous substance 

 which the insects collect from various trees. A mite which is parasitic 

 on some beetles is spoken of and figured as the beetle-mite ; this is mis- 

 leading, as the true beetle-mites are not parasitic, and have received 

 the name of beetle-mites on account of the hardness of their skins. 

 Attention has been called to various inaccuracies which have been noticed 

 in looking through this work, but they do not really detract from its 

 value, for it is well calculated to serve the purpose for which it was 

 written. 



VOL. XXXIV. S 



