MICROSCOPIC DRAWING AND ENGRAVING. 
These larvae swim with great agility, the hind legs acting 
together in concert like those of a frog; the antennae being at 
the same time erected, and the palpi concealed. The voracity of 
this creature is not directed alone to aquatic insects, hut proves 
often very destructive to young fish in fish-ponds. Mr. Anderson, 
the curator of the Chelsea Botanic Gardens, informs Mr. "West- 
wood, that he suffered much from these insects attacking young 
gold and silver fish, eating their dorsal and pectoral fins. 
Dr. Burmeister also mentions, that a specimen which he kept, 
devoured two frogs in the space of forty hours, and, nevertheless, 
when he dissected it shortly afterwards, it was found to have 
entirely digested them. They are very fearless in their attacks, 
seizing insects much larger than themselves. They employ their 
fore-legs as claws in seizing their prey. 
A specimen which Esper kept in water alive for three years and 
a half, feeding it with raw beef, is recorded by Clairville to 
have destroyed a specimen, twice its own size, of the large 
hydruspicius, piercing it with its jaws, at the junction of the head 
and thorax, its only vulnerable point. Dr. Esper observed that 
his specimen sucked the blood of the bits of meat with which he 
furnished it, and that the residue of them appeared like small 
white masses floating on the water. 
According to Esper and Erichson, they are, however, able to 
fast for many weeks, and even months, provided they are kept in 
water, but die, if withdrawn from it, in a few days. They are 
observed to ascend frequently to the surface to obtain air for 
.respiration, where they may be observed in sunny weather resting 
with the extremity of their body protruded above the water, and 
their legs extended at right angles. 
They may be often seen in a calm summer evening issuing from 
the water and creeping up the stalks of rushes, from which, after 
a little time, they take flight, rising into the air perpendicularly 
until they are out of sight. Their descent is also perpendicular, 
dropping with considerable force into the water. It would also 
appear that it is by the reflection of the light from the surface of 
the water, that they are informed of a proper place for their 
descent, Mr. Westwood having several times seen them fall with 
violence upon glazed garden-frames, which they had evidently 
mistaken for water. 
They are to be found in all seasons of the year, but more fre¬ 
quently towards the autumn. During the winter some remain in 
the water, or bury themselves in the mud, in a torpid state ; others 
retain their agility, and may be seen coming to take air in 
places where the ice is broken. Mr. Westwood has seen them even 
swimming about in the water under the ice on which he was skating. 
, 88 
