152 REMARKS ON TRICHIOSOMA LUCORUM. 



SO that it merely hangs by a little hinge; this they perform with theii* 

 mandibles, (which are very strong, sickle-shaped, with two small teeth,) as 

 true as it could be done with a pen-knife: it requires about two hours work. 

 In one instance the fly made a shght error in judgment, for when it had 

 cut out the piece the hole was too small, and after several vain attempts 

 to get out, it began and cut off a thin strip round the hole, which made it 

 large enough. I believe when they begin to work they soften the wall of 

 the cocoon with an acid, for, as soon as their mandibles get through, a little 

 liquid oozes through the opening, which has a very powerful smell. 



My first flies came out on 12th. April, the day after I placed them in a 

 sunny window, and they became very active; I put them upon some hawthorn 

 leaves, but without any idea that I should soon have the pleasure of a sight 

 which I think but few have witnessed, namely, the act of ovipositing. I was 

 able to afford some friends a view of the operation, who declared it to be 

 one of the most beautiful sights they ever saw, and these parties are conversant 

 with the wonders of the microscope. A fly would continue to oviposit, at 

 intervals, for three or four hours, and was so intent upon it that I could 

 turn the leaves about so as to be able to see the whole operation distinctly 

 with a Coddington lens. It would seem that, although there may be no 

 connexion with the male fly, the desire of propagating the species is equally 

 strong. When a fly has the desire to oviposit, and is placed upon some 

 hawthorn leaves, (for I find she will use no other leaves, the ovipositor 

 perhaps not being adapted for them, and the fly's instinct telling her that 

 the food is not suitable for her progeny,) she becomes restless, running 

 rapidly over the leaves with her antennae lowered in front, till she finds a 

 leaf in a favourable position; she then gets to the edge of it, begins to pierce 

 the leaf, and inserts the ovipositor and sheath under the cuticle, working the 

 saws rapidly, so as to raise the cuticle from the parenchyma, till the ovipositor 

 is wholly extruded: when it is withdrjiwn a fluid is injected into the small 

 space where it has worked, which makes the leaf have the appearance of a 

 little blister upon it. The cuticle is so very transparent that at a little 

 distance the ovipositor absolutely appears to be on the outside of the leaf. 

 I found, with gathered leaves, that the fly would use either side. The 

 operation takes about three minutes, during which time the fly lowers her 

 antennae in front, and the posterior segments of the abdomen have a slight 

 tremulous motion. The ovipositor is composed of two beautiful saws, slightly 

 turned at the ends, which work in the sheath: this is a case which opens 

 all its length on its top side, and about half its length from the end on 

 the lower side, but joined towards the base, so that at the end it opens as 

 if it was a spring. 



As regards the changes of the insects, I can only say that in the middle 

 of March I cut open a cocoon, and the occupant was then only a common- 

 looking grub; in a month after it cut its way out, and came forth a perfect 

 fly. It would be called a bee by persons not conversant with the insect, 



