mons themselves vary in size according to the 

 dimensions of the bodies on which they are des- 

 tined to prey. " Some," says Mr. Kirby, " are 

 so inconceivably small, that the egg of a butter- 

 fly, not larger than a pin's head, is of sufficient 

 magnitude to nourish two of them to maturity; 

 others so large, that the body of a full-grown 

 caterpillar is not more than enough for one." It 

 is not the Ichneumon itself, but its larvae or 

 maggots which destroy such quantities of insects. 

 The Ichneumon is a fly with four wings, whose 

 food is honey; and the female seems to live only 

 for the purpose of depositing eggs in the way 

 mentioned. 



" In search of this," we are told by the aged 

 entomologist just alluded to, " she is in constant 

 motion. Is the caterpillar of a butterfly or moth 

 the appropriate food for her young, you see her 

 alight upon the plants where they are most usu- 

 ally to be met with, run quickly over them, care- 

 fully examining every leaf, and, having found 

 the unfortunate object of her search, insert her 

 sting into its flesh, and there deposit an egg. In 

 vain her victim, as if conscious of its fate, writhes 

 its body, spits out an acid fluid, menaces with its 

 tentacula, or brings into action the other organs 

 of defence with which it is provided ; the active 

 Ichneumon braves every danger, and does not 

 desist till her courage and address have insured 

 subsistence for one of her future progeny. 

 Perhaps, however, she discovers, by a sense, the 

 existence of which we perceive, though we have 

 no conception of its nature, that she has been 

 forestalled by some precursor of her own tribe 

 that has already buried an egg in the caterpillar 

 she is examining. In this case she leaves it, 

 aware that it would not suffice for the support of 

 two, and proceeds in search of some other yet 

 unoccupied." Such are the singular habits of 

 these creatures, thus aptly described. All these 

 processes are, as might be expected, varied ac- 

 cording to the number of eggs that may be placed 

 with a hope of safe existence in any one body. 



As soon as these eggs are hatched, the young 

 maggots revel in the feast the body of their 

 victim provides, while the supply of food in every 

 instance is regulated with an inconceivable pre- 

 cision, so as just to last these young Ichneumons 

 till they have grown to an age to do without it. 

 Then the grub or caterpillar on which they have 

 existed dies, or perhaps just retains sufficient 

 vital power to turn into a chrysalis, which at last 

 does not give birth to a moth, butterfly, or any 

 other fly proper to it; but to one or more full- 

 grown Ichneumons, whose larvae have become 

 pupae within this case. The author, not many 

 years ago. had a chrysalis which disclosed at the 

 proper time, no less than seventeen Ichneumons, 

 instead of a large moth which he had expected 

 to see emerge from it. Instinct, we are told, 

 upon high authority, is a propensity prior to 

 experience, and independent of instruction : it is 

 verified in these strange operations. The little 

 maggot which springs from the egg of the Ich- 

 neumon goes on eating up its prey, devouring 

 every part of it except the vital organs, which it 

 never touches, as if it knew instinctively that the 

 death of its victim would involve its own entire 

 destruction by famine. Some Ichneumons only 

 glue their eggs to the bodies of certain larvae, 



because their maggots are provided with instru- 

 ments for piercing the skin. Others, like the 

 Cuckoo among birds, lay their eggs in the nests 

 of insects, which hatch them to devour their own 

 young. Bees are particularly subject to such 

 insidious enemies. No concealment, unless 

 perhaps under water, seems sufficient to baffle an 

 Ichneumon, and nothing can surpass its perse- 

 verance until its eggs are safely placed in the 

 condition suitable to its progeny." 



The following would seem easy of proof to all 

 persons. In regard to Ichneumon tipulae, now 

 called Platygaster tipulae, Mr. Sydney says, 

 " This little Platygaster may be readily found on 

 the glumes of the wheat plants in the months of 

 July and August. It runs rapidly over the ears, 

 and seems to know well which are those occu- 

 pied by the larvae of the midge. The author 

 found numbers of them in various wheat-fields 

 in August, 1845; and almost invariably, on exa- 

 mining the ears on which they appeared, disco- 

 vered they contained the object of their^search. 

 The Ichneumon hunts for them with the utmost 

 eagerness, and by the aid of a sharp tail places a 

 single egg in each of their bodies. The sight 

 has been witnessed by Kirby, by the following 

 experiment: — A number of larvae of the wheat 

 midge were put upon a piece of white paper, 

 pretty near each other, and an Ichneumon was 

 dropped into the midst of the group. The 

 energy of her manner, the rapid vibrations of her 

 antennae, and the whole of her attitudes, were 

 most amusing. On approaching one of the larvae, 

 her agitation quickened to the utmost intensity; 

 she soon bent her body in a slanting direction 

 beneath her breast, applied her tail to the larvae, 

 and, becoming still as death, sent forth her curious 

 sheath and deposited her egg in the victim, which 

 writhed considerably under the operation. If 

 she came to one that had previously an egg in it, 

 she left it in an instant, and sought another, for 

 the Platygaster lays but one in each. This how- 

 ever , often repeated, destroys a great many "of 

 these devastators of the grain." 



Each species of Ichneumon is restricted in its 

 attacks to one, or at most to a few, particular 

 species of caterpillars. Mr. Stephens states that 

 he possessed eight hundred British species of the 

 Ichneumonidae. From the foregoing, I think it 

 would appear there is abundant proof that Ich- 

 neumons pierce insects in the larva state. Speak- 

 ing generally, it will be found that writers upon 

 the subject say that it is while in the caterpillar 

 state that insects are attacked; and it seems 

 much more natural to suppose it should be when 

 in this soft state than when the insect lias put t»n 

 a stout protecting case, as during the chrysalis 

 period. I should hardly think it possible for the 

 Ichneumon, which is parasitic upon Trichiosoma 

 lucorum, to pierce with its slender ovipositor the 

 tough and leathery cocoon of that Saw-fly. 

 Doubtless certain species of insects are attacked 

 in one stage of their existence, and in that only. 

 It would not be supposed that the same Ichneu- 

 mon fly would attack an insect both in the larva 

 and chrysalis state. That the larva are really 

 attacked there can be no doubt; for I find it s-tated 

 in the " Penny Cyclopaedia," by Mr. Water- 

 house, I presume, that " Instances are not un- 

 common in which the eggs of the Ichneumon 



