Videnskabelige meddelelser

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Videnskabelige meddelelser

8

f)hili(ia' from nature is almost incredible. The larvæ of Hijdro-

philidiv are rather difficult to Hnd and apart from 2— ?> species

all are very small ; they are little known and most of them re-

garded as rare. The „Wasserkaferlarven" can by Piers i g really

only signify larvæ of Dytiscs; on the other hånd from Blunck's

and my own observations 1 am inclined to maintain that these larvæ

as carriers of larvæ of mites in nature itself only play a very in-

conspicuous role.

I suppose that Piersig has only been interested in getting

larvæ and nymphs for description ; he

has then got the Hydrach-

nids to lay eggs in aquaria, has hatched the larvæ and for their

further development furnished them with the most casual material

of aquatic insects he could get. The unhappy larvæ have made

a virtue of necessity and really developed into nymphs. But from

this result Piersig is by no means permitted to present the mat-

ter as if the larvæ of Hydrachnids in nature are parasitic upon

all aquatic insects indiscriminately and in this respect by no means

are tied. Perez besides (1904, p. 263) has maintained quite a

similar opinion Piersig goes so far that on p. 17 he indicates

Krendowsky's correct observation that the larva of .4r/7?

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