( xxvii ) 
viz. that the lai’va of S. undulata infolds itself in leaves in 
much the same manner as Tortrices do. It seems very probable 
that the shelter thus afforded may be of some importance to 
the X. comtus larva, which has a much more delicate cutaneous 
envelope than have most of the Syrphid larvae feeding exposed 
on Aphides that I happen to know. The shelter must be of 
use, as it is to its victims, to hide it from its enemies, and the 
delicate skin may be a result or a further cause of the sheltered 
existence. Probably the larva searches for the shelter of its 
next victim during the night when neither sun nor predaceous 
enemies are to be dreaded. 
It follows from all these facts and considerations that 
Pi’ofessor Poulton’s beautiful theory as to the alternative 
instinct displayed by the female of A", comtus, though of the 
very highest interest if it could be established, may be regarded 
as without the slightest foundation. 
The remai’ks to the disparagement of the egg-laying instincts 
of the Spliingidac must, of course, fail as a matter of compari¬ 
son with the instincts of X. comtus, and per se, the presence 
of an unduly large number of larvae on a very small bush is 
an occurrence that one not unfrequently meets with in other 
insects and elsewhere. 
It is the result of one particular bush presenting flavours 
or other attractions to more than one moth, or to the same 
moth over and over again, after it has gone in search of a 
suitable place elsewhere. . A striking and not infrequent 
instance is where a young pine-tree is nearly or actually 
killed by a large number of nests of C. ^ntyocampa, whilst 
numerous trees around, to our eyes much more tempting, 
are untouched. A similar common case which most of us 
have met with is in the case of Aglais urticae, where a brood 
of larvae may be found on a patch (if it amounts to a 
patch) much too small to nourish them all to full-growth. 
Such a case usually occurs when the butterfly is very common, 
and I have seen even large areas of nettles with a number of 
broods more than sufficient to demolish it. All these cases 
are, broadly, the results of over-population. 
Mr. J. 0. Kershaw contributed a paper on “ The Oothecae 
of an Asilid (Promac/ms sp.).” 
