Hydrophilus triangularis

[Hydrophilid]

Hello All,

I am currently raising about 30 Hydrophilus triangularis larvae in a communal setup. Two of my adult females produced oothecae back in July. I tried raising those larvae in individual setups but they all died, with only a couple making it to 2nd instar. I think this may have been due to poor water quality keeping them in such small containers.

Another female produced an ootheca recently and I decided the raise the larvae in a heavily vegetated communal setup. Although there has been some cannibalism, the growth has been much better, with all larvae currently in the 2nd or 3rd instar stage. Cannibalism has slowed down in the group and I expect a good number to fully develop.

My question to the group is, does anyone have any recommendations for dealing with the pupal stage of this species? My understanding is that they would normally leave the water and dig a pupal cell/chamber on dry land. Any suggestions on how I could set this up or simulate these conditions? Any advice from those who have experience with aquatic beetles would be appreciated. 

Cheers,

Daniel

 

[Dynastes]

put 1/2" styrofoam across one half of the top with an inch of dirt and pieces of flat bark covering much of the dirt. They should make them under the bark. Have any cool photos? 

 

[Hydrophilid]

Thanks for that suggestion! I think I will put together something like this. I may PM you with some questions as I go about it.

Here are a few photos of a couple of my adults. I used to have two pairs, but now I am down to 1:2, male:female.

 

[Hydrophilid]

Here some oothecae that they have produced. There is a bit of floating vegetation stuck to the silk "buoy."

 

[Hydrophilid]

Here are some 1st instar larvae. They have done quite well feeding on frozen/thawed bloodworms.

 

[Hydrophilid]

Here are the 2nd and 3rd instar larvae. They develop the dark pattern and wider heads when they reach 3rd instar.

 

[Hydrophilid]

They've begun to pupate.

 

[Ratmosphere]

Great work @Hydrophilid that's definitely something you don't see often!