CHAMBERS'S INFORMATION FOR THE PEOPLE. 



and most are oviparous. Many insects undergo 

 changes of form (metamorphosis) in their de- 

 velopment from the immature to the adult con- 

 dition. Those which do not undergo this change 

 are called Ametabolic Insects (Gr. a, without, 

 metabole, change). The young of these insects 

 resemble their parents in all respects except 

 in size ; moreover, they are destitute of wings. 

 Those which only undergo a half-metamorphosis 

 are called Hemimetabolic Insects. They undergo 

 three stages. The young is termed larva; in the 

 second stage it is Pupa; and in the third, the 

 perfect insect or imago. The larva differs from 

 the imago in its smaller size, and in the absence of 

 wings, while the pupa differs from it only in the 

 wings being rudimentary. This metamorphosis 

 is said to be incomplete. Those which undergo 

 a complete metamorphosis are called Holometa- 

 bolic Insects. The larva is worm-like, feeding 

 voraciously, and growing rapidly. It is then called 

 caterpillar or grub. After frequently changing its 

 skin, it passes into the pupa or chrysalis state, 

 when it becomes incased by a coriaceous covering, 

 and seems all but devoid of life. Other larvae spin 

 for themselves a protective covering, which sur- 

 rounds the chrysalis, and is termed the 'cocoon' 

 (the Silkworm}, while others reside in tubes con- 

 structed by themselves (the Caddis-ivorni). Finally, 

 it emerges from this condition as the imago, or 

 perfect insect, with fully developed wings, ready 

 for flight 



SUB-CLASS I. Ametabola. The young pass 

 through no metamorphosis; imago destitute of 

 wings ; eyes, if present, are simple. It includes 

 three orders. 



ORDER I. Anoplura are typified by the Com- 

 mon Louse (Pediculus), a creature justly regarded 

 with loathing, because it never exists unless in 

 connection with dirty habits. The head bears two 

 simple eyes and a suctorial mouth. They are all 

 parasitic on mammiferous animals man, the dog, 

 and sheep having each an appropriate parasite of 

 this order. 



ORDER 2. Mallophaga are specially common 

 on birds, hence called Bird-lice. Their mouth is 

 suited for biting, and they live on the more delicate 

 portions of the feathers. 



ORDER 3. Thysanura 

 includes the Podurce, or 

 Spring - tails, which pos- 

 sess a forked tail, curved 

 under the animal, by sud- 

 denly extending which, 

 they are enabled to spring 

 to a considerable distance. 

 SUB-CLASS II. Hemimetabola in which the 

 metamorphosis is incomplete. This sub -class 

 includes three orders. 



ORDER 4. Hemiptera (hemi, half, pteron, wing). 

 Mouth suctorial, the labial palpi forming a 

 sheath for the style-like maxillae and mandibles, 

 and thus protecting them. With these bristles, 

 the insect pierces the plants or animals upon the 

 juices of which it feeds. The head bears a pair of 

 compound eyes, and usually also several simple 

 eyes. Most of them possess four wings. This 

 order is subdivided into 



SUB-ORDER (A). Homoptera (homos, like, and 

 pteron, a wing) in which the anterior pair of 

 wings are of similar consistence throughout, often 

 somewhat parchmenty, and the mouth looks 



146 



Podura villosa. 



backwards, so that the rostrum springs from the 

 back of the head. These are represented by the 

 Cocddce (Blight Insects) for example, the Coccus 

 cacti (Cochineal Insect), esteemed for the splendid 

 colour it furnishes. It takes seventy thousand of 

 these insects to make a pound of cochineal An 

 East Indian species (Coccus lacca) yields shell-lac 

 and lac-dye. In these cases, it is only the female 

 insect that yields the colouring matter. The 

 Aphides (Plant-lice) inhabit trees or plants, to 

 which they prove highly destructive, feeding, as 

 they do, upon the juices they contain. They ex- 

 hibit some very peculiar phenomena in their 



Fulgora laternaria. 



manner of reproduction. The Fulgora laternaria 

 (Lantern-fly of Guiana), in which the forehead is 

 much prolonged, is said to emit light in the dark. 

 The Aphrophora spumaria, or Frog-hopper, a 

 British species, also belongs to this group. Its 

 larva envelops itself in a frothy secretion, which 

 has received the name of ' cuckoo-spit.' The 

 Cicada was celebrated by the Greek poets for its 

 fine song, peculiar to the male, and produced by 

 the vibration of a drum-like organ situated at the 

 side of the abdomen. 



SUB-ORDER (B). Heteroptera, or Bugs (heteros, 

 different, pteron, a wing) in which the wings are 

 chitinous towards the base, and membranous 

 towards the point, the beak springing from the front 

 of the head. The Boat-flies or Water-bugs (Noto- 

 nectd) haunt the surface of still waters. They use 

 their hind oar-like feet for swimming, and with 

 their anterior pair they seize their prey. The 

 Nepida (Water-scorpions) are fierce insects, and 

 lurk in ponds, living solely on insects. The Cimi- 

 rida (Bugs) are unhappily familiar to us, by their 

 intrusion into our bed-chambers. When irritated, 

 they emit an offensive odour. 



ORDER 5. Orthoptera (orthos, straight, pteron, 

 a wing). The mouth is admirably suited for bit- 

 ing ; wings four, the anterior pair of a leathery tex- 

 ture, and forming a protection for the posterior, 

 which are larger, and folded in a fan-like form. 

 This order contains two sections. The first of 

 these sections, the Saltatoria, are all herbivorous 

 insects, and have the hind-legs elongated, and 

 fitted for leaping. It includes the family of the 

 Locustina (Locusts), so common in warm climates. 

 ' Wherever they alight, all signs of vegetation dis- 

 appear, and cultivated grounds are left a desert.' 

 The most common species is the Locusta migra- 

 toria, which is so formidable an enemy to agri- 

 culture in Southern Europe, and even reaches our 

 own island. The Gryllina (Grasshoppers) have 

 very long antennae, and the largest British species 

 is the Gryllus viridissimus, measuring about two 

 inches in length. They are so pugnacious that if 

 two are put into a box, they almost invariably 

 fight, and the victor dines off the legs of the 

 vanquished. The other British species are all of 



