142 MODERN CLASSIFICATION OF INSECTS, 
their food, and of the objects fitted for the reception of their eggs. 
Some species (Ophion) are, however, less agile, not vibrating their 
antennze. 
These insects are of vast importance in the economy of nature, by 
preventing the too great increase of different species of insects, 
especially of the caterpillars of butterflies and moths, of which they 
destroy a great number, it having been observed that a super- 
abundance of any species of insect is attended with an increased 
production of its parasitic enemies.* 
The females exhibit a wonderful instinct +, in discovering the 
proper receptacles for their eggs, consisting of the eggs, larve, or 
pupz of other insects, as well as spiders. Those species which have 
the ovipositor short, attack exposed naked larvee and pupz; whilst 
those in which this organ is long, deposit their eggs in or upon the 
bodies of larve residing in the wood, or under the bark, of trees, or 
in deep crevices of the bark. In such cases, as I have often observed, 
the ovipositor is inserted in a perpendicular direction, the two ex- 
ternal pieces, or sheaths, being entirely disengaged, and often raised 
into the air. (See also Réaumur, vol. vi. ; and Marsham’s account of 
Ichneumon manifestator in Linn. Trans. vol. iii. p. 26.) 
Dalman, in his interesting memoir on this family, has made some 
curious observations as to the comparative numbers of these parasites 
and the other insects. (Swed. Trans. 1825; and in Bull. Sci. Nat. 
Ferussac, Jan. 1828.) 
There is scarcely a tribe of insects which is not subject to the at- 
tacks of these parasites, although it is chiefly amongst the Lepidoptera 
that their ravages are confined. Amongst the Coleoptera, Timarcha 
tenebricosa anda species of Coccinella and Curculio have been recorded 
by De Geer and Kirby. M. Audouin has obtained Microctonus ter- 
minalis Wesm., from the perfect Coccinella 7-punctata, the larva of the 
former bursting forth and spinning its cocoon beneath the body of the 
* Mr. Dale (Mag. Nat. Hist. No. 19.) gives an account of six specimens of 
Ophion vinulz, and a specimen of Bombyx menthrasti, “ hatched from the pup 
of Bombyx vinulus, which is certainly a curious fact.” 
+ The female of the remarkable species Agriotypus armatus is stated to have 
been observed on the banks of the Clyde to descend the sides of the rocks to a 
considerable depth under the surface of the water, remaining immersed for ten 
minutes and upwards, and then reappear without any apparent injury, repeating the 
operation several times; these subaqueovus wanderings being probably for the 
purpose of depositing its eggs in some aquatic larva, (Ent. Mag. vol. ili. p. 412.) 
