Videnskabelige meddelelser

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Videnskabelige meddelelser

47

ihe larvæ sitting on the base of the wings. By .S. imlgatum they

are said to be placed at the base of the abdomen ;

from

90 to

150 larvæ are found upon one single specimen. They sit along

the great nerves of the wings and pierce the mandibles into them.

Krendowsky shall, according to Musse! i us, have observed

that the larvæ during the parasitic life grow from O.2 to O.so mm;

from this we may suppose that they fetch some nourishment from

their base of attachment.

From the litterature it may therefore be regarded as a faet

that larvæ of Hydrachnids seek on to Odonaia\ Krendowsky and

Ris has seen them during the last ecdysis climb over upon the

imago. In those cases where these larvæ have been determined it

has always been proved that they belong to Arrhenuri. Their

further fate is unknown.

It is very remarkable that Piersig (1900, p. 334) having in

the introduction mentioned Krendowskys discovery of A. papil-

/a/or-larvæ on the wings of Odonata (p. 17) in the diagnosis of

the genus (p. 274) says: „Samtliche Arrhenurus-Larven suchen

vor allem junge Kaferlarven auf um zu schmarotzen und sich zu

verpuppen." With regard to different species he often indicates

that the second pupa stage is to be found upon water piants. I

suppose that these reports by Piersig all refer to aquaria experi-

ments and as such, in my opinion, are quite valueless.

The 23 /V 1917 I was standing at the horders of Funkedam;

at that time Libellula quadrinmculata was leaving its nympha

skin. In thousands of individuals the insects were sitting upon the

Cyperaceæ bordering the pond ;

on

one of the specimens head and

thorax had burst the skin, but the abdomen was still sitting in it.

To my astonishment I then saw a little society of six red larvæ

of mites running eagerly over the soft skin of the animal; on the

old nympha skin none were left. During a quarter of an hour the

Libellula had left the skin and now hung upon the empty skin to

be dried in the vernal air. During that time all the mites fast-

ened themselves on the ventral side of the abdomen and only in

the two longitudinal furrows. The 17 V 1912 I was once more

upon the same spot. At that time Cordulia ænea left the nympha

skin. In thousands of individuals the insects hung in all stages

of development some few decimeters above the water. Furnished

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