80 



The Naturalist. 



these parasites, and they undoubtedly play a primary part in the great 

 drama of life. They counterbalance, and check the destructive and 

 ruinous approaches of other insects. The superabundance of one insect 

 is attended with an increase of its watchful enemy, the ichneumon. 

 Were the lovely green moth, Tortrix viridana allowed to roam un- 

 molested through Britain's avenues of oaks, those noble trees would be 

 almost entirely stripped of their foliage. Thousands of these moths 

 are destroyed annually in their pupal stage ; thousands perish when 

 they have assumed their verdant robes ; on one hand by the ichneumon, 

 on the other by its dipterous enemy the Empis. 



Unfortunately for the further progress of Hymenopterology, Coleoptera 

 are seldom collected in the larval state, and therefore their parasites 

 are, with a few exceptions, unknown. That they are not exempt from 

 parasitical attacks, is evident from the fact that an ichneumon {Microc- 

 tonus terminalis), has been bred from the perfect Coccinella septem- 

 punctata.^^ Nothing less than a few researches in this direction will 

 be necessary to bring many new facts to light. Aphides are par- 

 ticularly liable to ichneumon attacks, and were such not the case, the 

 destruction these little insects cause woald be increased a hundred 

 fold. A single egg, only, is deposited in an individual Aphis, and the 

 infected insect renounces all companionship, taking up a position on 

 the underside of the leaf. The ichneumons do not confine their attacks 

 to other orders, but feast with evident enjoyment upon one another, 

 and are then said to be hyper-parasitical. Ichneumon larvae, from a 

 slight resemblance to the Annulosa, are therefore said to be vermiform ; 

 as they lack ambulatory organs, are likewise termed apodal. It is 

 quite evident that such appendages would be utterly superfluous, for 

 nature has supplied the parent insect with an instrument, by the aid 

 of which she is enabled to place her otherwise helpless offspring in a 

 situation where they will be able to attend to their own interests. The 

 whole of the hymenopterous larvae are without legs, excepting one 

 family, the Tenthredinida, or saw-flies, the larvae of which very much 

 resemble those of Lepidoptera. Ichneumons in their second stage are 

 soft, fleshy grubs, slightly attenuated at each extremity, and armed 

 with two mandibles. 



Their instinct teaches them that they must confine their attacks to 

 the fatty portions of the animal, and carefully abstain from ariy 

 destructive raids upon the viscera. Now the caterpillars of Lepidoptera 

 are vegetarians^^ (except when they think proper to exercise a certain 



1 0 Westw. Class of Insects. Vol. 2, page 142. 

 1 1 Another familiar exception occurs among the micro-lepidoptera, some species 

 feeding upon wool, fur, etc. 



