220 DISEASES OF INSECTS. 
which forms galls upon the juniper is devoured by an ex- 
ternal Ichneumon?; that which injures the wheat in the 
ear, whose ravages I formerly mentioned to you>, af- | 
fords food to three of these parasites,—one I lately men- 
tioned as probably devouring its eggs; another pierces 
the glumes of the floret, where its ceed prey is con- 
cealed; and the third enters it. I once placed a number 
of the larvee of the gnat upon a sheet of paper, at no 
great distance from each other, and then set down one 
of these last Ichneumons in the midst of them. She be- 
gan immediately to pace about, vibrating her antenne 
very briskly: a larva was soon discovered, upon which 
she fixed herself, the motion of her antenne increasing 
intensely; then bending her abdomen obliquely under 
her breast, she inserted her ovipositor, and while the 
egg was depositing these organs became perfectly mo- 
tionless. The larva when pricked gave a violent wriggle. 
This operation was repeated with all that had not al- 
ready received an egg, for only one is committed to each 
larva. I have often seen it mount one that was already 
pricked, but it soon discovered its mistake, and quitted. 
it untouched*. ‘The only other Dipterous insects that I 
have seen mentioned as affording pabulum to an Ich- 
neumon, are—one of the aphidivorous flies mentioned by ) 
De Geer, who does not note the species, to the larva of 
which the Ichneumon commits only a single egg, pro- 
ducing a grub that entirely devours its interior 4 ;—and 
two qeccuhad by Scopoili, one, the larva of a Sty frequent- 
a De Geer vi. 411—. Vou. Eppa: 
© Linn. Trans. iv. 236. 4 De Geer i. 605. This, as be- 
fore observed, is not the 2. Muscarum of Linné ; but it ought to have 
that name, and the other instead to be named J, Coccinelle. 
