Videnskabelige meddelelser

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Videnskabelige meddelelser

21

enigmatical, why the mites attach themselves to this fully dead tis-

sue as the elytra really are. It seems as if these at the point of

attachment are fully unaltered ; only a little dot showed where the

parasite had been attached. That they should here get any nour-

ishment is almost impossible. As far as I know we have- never

previously found the parasitic stages of Hydrachnids on the u'ing-

covers of Dytiscidæ. the Hydrachna larvæ always being fastened

to the abdomen, head, thorax or legs. —

If we now compare Duges' and Krendowsky's statements,

that the young Eylæis larvæ are parasites upon Tipulidæ and

Odonata, with my observation that the nymphs are hatched from

waterbugs and Dijtiscidæ and remember that Thon has main-

tained that the fullgrown Eijlæis hatch directly from these insects

one would be inclined to think that here by Eijlæis we have found

a change of host by the Hydrachnidæ not hitherto observed. Fur-

ther remembering that it is almost impossible to suppose that the

delicate Tipulidæ should be able to carry the relatively heavy

nymphs, that these have never been found upon aérial insects

and that the nymphs of Eylæis, as far as I know, are always re-

markably large, it may be presumed that this supposition can be

correct. However, at this moment, this supposition has no more

value than that of a working theory, but as such I hope it will

be used in the following years. Further it must not be forgotten

that most probably Krendowsky and I have observed different

stages in the development of quite different species. Until we

have been able to follow the development of the very same species

from sixlegged larva to imago in all its stages of parasitic life we

do not know whether Eylæis makes a change of host or not.

However an exploration of this kind is very difficult to carry out.

Hijdiijphantidiv.

Our knowledge of the development of the Hydryphdntidæ is

restricted to the two genera Hydryphantes and Diplodonlus, espec-

ially H. riiber (Degeer) and D. despiciens (O. F. M).

Hydryphantes.

According to Neuman (1880, p. 113) and Pi er si g (1900, p.

392) the eggs of H. ruber are laid upon waterplants. Soar indic-

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