87 
features adapting it for insect rearing, however, have been introduced 
by Mr. Pergande, and the result in our own case is very satisfactory. 
Two glass aquaria each 2£ by 1J by 1J are placed end to end, the one 
elevated on a three-inch base so as to make it that much higher than 
the other. The water connections from the one to the other are so ar- 
ranged that each may be independent of the other, and the details are 
simply arranged. In each a V -shaped inclined glass septum with a 
broad deflexed lip, and beneath this lip has been constructed an arti- 
ficial rock- work grotto. The water enters the first aquarium through 
a T sprinkler with six pipette orifices. It drops a distance of 6 or 8 
inches into the V sna P ea septum and its force is easily graduated by 
stop cocks. Eising to the height of the deflexed lip it pours in a broad 
cascade into the main compartment, impinging on the top of the rock- work 
grotto. The second or lower aquarium is at present similarly arranged, 
and derives its supply of water either from the overflow of the first or 
independently from an overhead pipe, so that its water may be kept 
either still or running at will. Thus we have arrangements in a small 
space for the rearing of all kinds of aquatic insects. The sliding 
stream upon the artificial rock- work is particularly adapted for such 
forms as Simulium, and opportunity is also offered for such species as 
have the habit of crawling out either on rocks or earth, as the case 
may be. 
One of the difficulties encountered in the rearing of insects is the 
proper maintenance of the right degree of moisture. Galls of all 
kinds, whether cynipid, cecitlomyiid, or trypetid, are apt to be left 
either too dry, in which case the issuing of the adult is delayed far 
beyond the normal time, or too moist, in which case they become cov- 
ered with mildew and spoil. If the jar containing them be left open 
they dry, no matter if sprinkled frequently. If the jar, on the con- 
trary, be stoppered, mildew soon puts in an appearance. This difficulty 
is obviated by keeping all galls in a series of jars at the same height, 
the mouths of the jars being covered with gauze to prevent the escape 
of the adults or of parasites. Over the whole series is laid a large 
sheet of blotting paper. The blotting paper is moistened daily, and 
gall in insects seems to thrive under this treatment. Mildew seldom 
appears, and the insects emerge on time. This same plan is a good 
one for certain tineids. 
The subject of moisture in the rearing of lepidopterous larvae has 
been frequently considered, and it is a tolerably well-known fact that 
it is disastrous to feed these larvae wet foliage. Spraying the leaves 
upon which they are at work has been practiced, but both practices 
result in a diarrhoeic disease which carries off whole' colonies, just 
as the same course is followed by the same trouble with the domestic 
silkworm. As a matter of fact, lepidopterous larvae do not feed dur- 
ing a rain or upon wet foliage out of doors, as many observers will 
testify. 
9052— No. 2 3 
