The Garden Guide

Book: The Principles of Landscape Gardening
Chapter: Chapter 1: Entomology as Applied to Gardens


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1640. HYMENOPTERA. The wings are four in number, transparent, of unequal size, the fore pair being the largest, and with but few reticulations. The mouth is furnished with strong jaws for biting; the body of the female is armed with a sting or borer; and the larvᄉ (with the exception of those of the saw-flies) are fleshy grubs destitute of legs; whilst the pupᄉ are inactive, resembling those of beetles. Many of the insects in this order are more intelligent, and more beneficial to man, than any others. The different species of honey-bees, in all parts of the world, supply him with honey. The ant, particularly in tropical countries, is the grand promoter of vegetable decomposition; and the innumerable hosts of ichneumon flies carry on a perpetual warfare with various descriptions of caterpillars that infest vegetation. Some of the species, however, are to be regarded as obnoxious insects, amongst which are to be especially mentioned many of the species of saw-flies (Tenthredinidᄉ), the caterpillars of which are furnished with numerous legs closely resembling those of butterflies and moths, and which, like them, feed upon the leaves of various species of plants. Amongst these is the black jack, or nigger caterpillar, being the larva of Athalia centifoliᄉ, which in certain seasons proves one of the most obnoxious of our insect enemies, by devouring the leaves of the turnips which have been spared by the turnip flea-beetle. These larvᄉ are very voracious, and shed their skins several times. When full grown they descend into the ground, forming an oval cocoon of agglutinated earth at the depth of several inches, the interior of which they plaster over with a white shining secretion, and within which most of the individuals remain until the following season. The larvᄉ of different species of the genus Lophyrus are also very injurious in fir plantations and forests, destroying the young leaves, and often entirely killing the trees. Another species (Selandria ᆭ'thiops), belonging to the same family, often commits serious injury, by its larvᄉ feeding on the leaves of the plum and pear trees. In this state they are remarkable for being covered over with a black viscid matter, which exudes from the sides of their bodies, and which gives them the appearance of small slugs. It is the larva of another species (Nematus grossulariᄉ) which so often entirely defoliates our gooseberry trees; whilst Tenthredo testudinaria lays its eggs in the bloom of the apple, the young larvᄉ as soon as hatched eating the core of the fruit when it is about the size of a walnut, and so causing it to fall. Several species of Lyda form portable cases of bits of the leaves of roses, aspens, and nut-trees, which they cut from the tree and roll up with great ingenuity. Cephus pygmᄉ'us, in its larva state, is very destructive to young wheat plants. The species of the family Siricidᄉ are also very destructive, the larvᄉ burrowing into the solid wood of various trees, especially of the fir and pine tribes. Sometimes, indeed, they appear in such great numbers in the neighbourhood of the great German pine forests as to raise alarm in the minds of the ignorant, these species, especially Sirex gigas, being among the largest insects of the order. The species of Cynipidᄉ may also be considered as injurious, on account of the galls of different kinds which they form upon various kinds of plants, thereby disfiguring them; of these the oak apple, and bedeguar or hairy gall of the dog-rose, are common examples. The round galls on the shoots of the oak (fig. 290. j) are caused by the Cynips quercus folii (k). The gall nut of commerce is caused by the puncture of another species (Cynips gallᄉ tinctoriᄉ) upon a species of oak in the Levant; and the benefits which have resulted from its use in the manufacture of ink are more than sufficient to outweigh the injuries committed by the other species in the same family. Many of the species of this order may also be considered as partially obnoxious on account of the sting with which the females are armed; but most of these sting-bearing species are serviceable by destroying great numbers of caterpillars, flies, &c., which they collect and lay up in their nests as a store of food for their progeny. These are generally found in the spring and summer months, and are known by the names of sand wasps, and solitary wasps; they are moreover smaller in size than the common wasp (Vespa vulgaris), which is one of the most injurious pests in walled gardens, feeding on ripe fruit, but also attacking meat, live insects, and, indeed, devouring almost every kind of article. These should be enticed into phials half filled with sugared water, or by treacle spread on a plate or tile, &c. But the most secure plan for their destruction is, to burn sulphur by night at the mouth of their nests, or to pour spirits of turpentine on a piece of cotton wool, which must then be thrust into their nests, the mouth in both cases being covered over with a sod.