About 10 days ago, I found 2 io's. They had just turned into their bright green color phase and were just over 1 inch long when I brought them home. Out of the usual brood of about 25, these were the only two I could find, and I know the io is quite rare locally.
Now my pillars are just over 2 inches, but as of yesterday, I noticed some dark spots suddenly having appeared on them, toward their rears, and along lateral line or sphiracles. They have not molted since I've had them, so I figure they are getting close to that time, but mine still eat. I do know from past experience, pillars stop eating before the molt.
I am still concerned about the spots, though. Any ideas what these may be from? Thanks for any help, because if these io's are parasitized, they will have to be destroyed.
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Sick/parasitized caterpillars?
Replies (4)
Sorry to hear about this 
As you probably recall from past experience that the heartline (runs down center)becomes more noticeable before pupation but not as noticeable on these as on a smoother type like luna, cecropia, etc.
I have lost cecropia to the Nuclear Polyhedrosis Virus (NPV) and one of their symptoms was black spots. Also look for runny frass (not the usual big poop right before spinning). I have linked you to an article.
I just took some nice pix of my io's today with oyu in mind! I will upload to webshots and give you a link. Let me know how you make out with these two.
Well, Lele, that is some interesting reading. No, it's not what I have. No color loss and normal frass. It's just that these dark spots are increasing. They started near the back end, but are now randomly the length of the larva, still focused along the sides. Their appetite has dropped off. I first noticed a single spot about 4-5 days ago.
I will keep these under close surveillance to see what happens. I just don't recall ever having reared an io or any other caterpillar that developed such spots.
have you ever seen parasitic wasp coccons on a lep? It is very distressing and sad to think that they are being eaten from the inside out (usually the case) thought there is debate on whether there is a numbing substance released so the lep feels no pain which makes some sense b/c then the larva (wasp) can continue to feed. it is a very sad thing indeed especially when you are so partial to these creatures.
If indeed the lep is parasitized you can decide to kill both the lep, therefore the wasps, or put them outside and let mom nature do her thing. I had to make that decision several times my very first year rearing. They were sphinx larvae which are very prone to parasitization. I opted for nature.
B/c nature keeps balance I doubt that parasites have impacted the io pop. to near extirpation. More likely, as you know, it is due to habitat loss and pesticide use. GRRRRR!
On an up note - I have posted my little leps to webshots
lele's webshots
Well, Lele, as much as I hate to do it, I've made the decision to kill one of those larvae today. I'm going to do a careful dissection to look for any developing larvae. I've seen the little cocoons before on sphingids. I know it's the dirty work of the braconid wasps. I fear mine are victims of tachinid flies. The tachinid is another nasty parasite of many caterpillars. The ichneumon infests a lot of io's and other saturniids. I do believe in areas with heavy ichneumon populations, it is prudent to control their numbers with a bug zapper.
I've never felt comfotable just letting nature take its course on parasitized caterpillars, unless they were really a true crop/ornamental pest. There are way too many gardeners routinely protecting their crops with safe [as well as some unsafe] insecticides, to allow just more braconids to terrorize the community.
Yes, I agree with the overuse of insecticides. As I've said before, in 20 some years, the trend in majo urban areas is complete lawn care programs, and white grub and ant control is included in the package. I have no doubt that these chems have a devastating effect on our ground-pupating saturniids and sublevel pupating sphingids. Also, speaking of ants, the imported fire ants are increasing in the south at an alarming rate, despite our best efforts to control or stifle them. These predatory insects may also be equally responsible for the destruction of many ground-pupating moths like saturniids and other species.
