430 



SCIENCE OF GARDENING. 



Part II. 



are both nearly of the size of the perfect insect To this genus also belongs the insect generally known 

 by the name of diamond beetle. 



2236. Dytiscus and hydrophilus are aquatic genera, inhabitants of ponds and stagnant waters, they swim 

 with great dexterity ; their hind legs are particularly fitted for their residence in the water, being thin 

 and flat, and having the inner edges furnished with stiff hair-like appendages which act as fins or oars; 

 the males are distinguished from the females, by having a horny flap or shield on the fore legs, near the 

 setting on of the feet. The larvse (as is common with aquatic insects) remain a long time in the imperfect 

 state, some two to four years ; they secrete themselves in holes in banks, and devour other insects, worms, 

 and the voung fry of fish, which they destroy by sucking out their juices. 



22-37. The earwig {Forficula) frequents moist ground, is very injurious to flowers and fruit, and may 

 easily be taken by suspending any hollow article on a plant or twig, as it retires in the daytime to such re- 

 treats, and feeds mostly during the night. 



2238. The hemiptera are all furnished with wing-covers of a softer texture than the 

 coleoptera ; these covers do not meet in a direct line as in that order, but the base of the 

 left wing covers the inner margin of the right ; in some, the wings nearly cross at the 

 tips ; the mouth is either situated on the breast, or inclining towards it. The principal 

 genera are — 1. Blatta (cock-roach) ; 2. Gryllus (locust, grasshopper) ; 3. Fulgora 

 (lantern-fly); 4. Cimex (bug, &c.) 



2239. Of the cock-roach {Blatta) many species are 400 

 exceedingly injurious, devouring most kinds of provi- 

 sions, paper, leather, and vegetable substances ; they are 

 generally nocturnal insects, and are found in great 

 abundance in bakehouses, and other warm places. 

 They are all killed without any external injury, by 

 immersion in boiling water. 



2240. The black cock-roach, improperly called the 

 black beetle {B. orientate) {fig- 400 -)» was originally a 

 native of South America, but is now very generally 

 spread throughout Europe. It cannot be considered a 

 British insect, though it frequents kitchens, ovens, and 

 warm places, and devours meal, bread, and other pro- 

 visions, shoes, &c. It conceals itself during the day, 

 and comes abroad in the night ; it runs quickly, and is 

 very tenacious of life. They are killed by red wafers. 

 The egg (a) is of a considerable size, and the pupa {b) 

 larger than the perfect insect (c). 



2241. The gryllus genus comprehends a number of spe- 

 cies,some of which are called grasshoppers,others locusts, 

 and others crickets. The caterpillars of the grylli have a 

 great resemblance to the perfect insects, and, in general, 

 live underground. Many of these insects feed upon the 

 leaves of plants ; others, which live in houses, prefer 

 bread and every kind of farinaceous substance. 



The house-cricket {G. domesticus) {fig. 401. a) is one 

 of those busv little insects that reside altogether in our 

 dwellings, and intrude themselves on our notice, whether we wish it or not. They are partial to houses 

 newly built, for the softness of the mortar enables them to form their retreats, without much difficulty, 

 between the joints of the masonry, and immediately 401 



to open communications with the different rooms. 

 They are particularly attached to kitchens and 

 bakehouses, as affording them a constant warmth. 

 In some of the warmer countries, this genus of 

 insects is, of all the pests that mankind are subject 

 to, the most injurious, destroying vegetables of 

 every kind and even from their numbers alone, 

 constituting one of the heaviest afflictions that can 

 happen to a country. The mischiefs done by the 

 blatta?, or cock-roaches, is trifling, compared with 

 those of this destroying tribe, for the dreadful ra- 

 vages committed by the locusts are such as to reduce 

 the most fertile fields to the appearance of barren 

 deserts ; they devour the fruits, leaves, and even 

 the buds and bark of trees, and have even been 

 known to devour he reeds ased in thatching the 

 human habitations, so unfortunate as to be visited 

 by these devouring hordes. Jackson depicts their 

 ravages in the empire of Morocco, and gives a figure 

 of the insect {fig. 402.) of half the natural size. In 

 Abyssinia, China, and other countries, the caterpillar 

 or larva of certain species of roaches and locusts is, 

 like that of some beetles (2232.), eaten by the natives. 



Thefrog-hopper,orcuckow-spifinsect{Cicada)t'eeds, 

 on various kinds of plants : the grub or larva is without wings ; in the pupa the wings are very short ; out in 

 both states they are exceedingly active. Themales-are distinguishable by their loud chirping note, the females 

 are quite mute". In the fly state, they are found on the leaves and stems of plants, and in the immature state 

 about the roots of grass and trees. The white froth- 

 like spittle, which is seen on the leaves and stalks of 

 many kinds of plants in the summer season, is pro- 

 duced by the black-headed frog-hopper {Cicada spu- 

 maria) (fig. 401. b), and if this froth be wiped off and 

 examined, it will be found to contain the larva or 

 young of the cicada : and this matter, which is dis- 

 charged from its own body, no doubt serves to protect 

 it from the attacks of other insects. 



2242. The plant-louse, vine-fretter, or puceron, 

 {Aphis) is a very common insect, the numerous species 

 being denominated from the trees and plants which 

 they infest. The males are winged, and the females 

 without wings ; they are viviparous, producing their 

 young alive in the spring: and also oviparous, lay. 



