Once a Week (magazine)/Series 1/Volume 6/Ichneumon flies and their predatory larvae
ICHNEUMON FLIES AND THEIR PREDATORY LARVÆ.
The entomological family Ichneumonidæ, to which belongs the race of four-winged flies whose larvæ prey upon the larvæ of other insects, has received its name from that of the little ferret-like animal, common in Egypt, which is said to feed upon the eggs of the crocodile. Just as the Egyptian Ichneumon destroys the crocodile in embryo by attacking the egg, so the larvæ of this race of flies destroy vast numbers of insects in their preparatory stages, by consuming the living caterpillar as their natural food, and hence the adoption of the term "Ichneumon " for one of the genera, and "Ichnenmonidæ" for the entomological group which includes this family of insects.
These parasitic flies deposit their eggs on the bodies of caterpillars, piercing the soft skin with a sharp ovipositing instrument with which they are furnished. The tribe of true Ichneumon flies have been popularly termed by French entomologists mouches vibrantes, on account of the continual and rapid vibration of their antennae, and also mouches triples, from the three hair-like appendages or triple tail with which they are furnished. and which is, in fact, the lancing instrument by means of which the skin of caterpillars and the shells of the eggs of certain insects are pierced. The engraving on the next page, which represents one of the largest of the family Ephialtes manifestator, will serve to show the appearance of the triple tail.
These Ichneumons which, in the early stage of their existence, feed upon the flesh of other insects, and which when they attain to their perfect state take only such innocent and delicate food as the honeyed syrup furnished by the nectaries of flowers, belong chiefly to the extensive order Hymenoptera, to which also belong the bee family and a great number of other insects having two pairs of transparent wings; but there is a certain other family of predatory flies, belonging to the order Diptera (comprising two-winged insects), which, though not termed Ichneumons, have yet the same instinct of depositing their ova on the bodies of insects, which those ova, when hatched, are destined to devour. Among these are several Syrphidæ, which deposit eggs on the larvæ of certain bees.
The true Ichneumons, as I have stated above, deposit their eggs on the caterpillars of certain butterflies and moths, and even on the eggs of some of the larger insects of that order, being Page:Once a Week Dec 1861 to June 1862.pdf/505 Page:Once a Week Dec 1861 to June 1862.pdf/506