Videnskabelige meddelelser

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Videnskabelige meddelelser

19

Hyhvis has been hatched from the larvæ having been parasites

upon these insects. Further it would be rather peculiar if even

the species of Eylæis, which also in the nymph stage, according

to the litterature, commonly belong to some of the larger water-

mites, should use flying insects as hosts and especially the very

delicate Tipiilidæ; it must be presumed that these insects were

not able to carry these relatively heavy parasites. At all events

we should expect that the parasitic life upon these insects would

not be carried on until after the hatching of the large nymphs,

but that the host was left in the sixlegged larva stage. If so, we

were, owing to the great difference in the size of this stage and

the nymph stage, almost compelled to suppose that a change of

host must take place before the first pupal stage, the sixlegged

larva leaving the aérial insect for search of another, upon which

it could reach its full size.

Comparing the assertion of Krendowsky with the following

observations it will be seen that this supposition can not be said

to be fully excluded. Still it must be remembered that Krendow-

sky's and my own observations probably do not refer to the same

species.

25 V 1909 I found in the svamp by Virum near the Furesø

many individuals of the little Cyniatia coleoptrata. Very many of

them were infested with a single great pearshaped Hydrachnid

parasite. This was sitting on the abdomen under the wingcovers,

these being lifted up on account of the large body, almost as large

as the whole abdomen of the insect. The bugs lived now in my

aquaria for abt. two months; however from 25th May to 5th June

a great deal died. The parasites were very annoying to the insects,

the great airroom beyond the wingcovers being neither respirator-

ically nor hydrostatically functionable. Still 6th June three nymphs

were hatched. To my great astonishment these nymphs did not

belong to the genus Hydrachna but to the genus Eyhvis. The

nymphs were immediately after hatching almost half the size of

the hosts. In the following two weeks the nymphs lived in my

aquaria and I had hoped to see them anchor themselves to a plant,

but this was not the case. Later on I have been in doubt whether

these stages being of such a large size really were nymphs and

not fullgrown individuals in this case leaving the host in the adult

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