I found several of these empty cocoons in a small oak tree in my yard. At first, I thought they were bird nests of some kind, but with about 7 in one tree, I don't think so. I opened one up (had to use scissors, you can't tear them!) and found stuff in them like a bug of some kind had hatched (that kind of brown, thin, shell-like stuff).
The cocoons are hanging on small branches in the tree, there is a hole in the top of it where whatever was in it exited. They are smooth like brown paper sacks inside and out and between the 'paper' is a really tough web like material.
Can anyone tell me WHAT might have hatched - not sure whether to spray the tree or leave it alone (good bugs or bad bugs?)
It might be a cecropia moth. They are beautiful. The catapillars are as big as your ring finger with spiky orange balls on their head and blue footpads. Mine were on a lilac bush. 9 of them . Next spring none of them hatched because something got them.
Thanks Billy - I looked up some info on them and from what I see, the cecropia moth attaches it's cocoon all along one side, these are attached just on one side of the top of the cocoon. It definately gives me hope that what came out of these are 'good bugs' though! We have a lot of hawk and hummingbird moths here, although I thought they morphed underground . . . hmmm - perhaps I need to check on that.
I think it's a Polyphemus moth cocoon (Antheraea polyphemus) - same type of moth as the cecropia (Saturniid moths aka giant silk moth family). Please don't spray the tree with anything if you see them. They are beautiful moths and all of them are becoming less common with the loss of habitat and increased use of pesticides. The caterpillars won't do any permanent damage to a well-established tree.
I host Cercropias on my Filberts (Corylus avellana) and wouldn't care if they defoliated a whole tree. As it is, I can sometimes find a couple of chewed leaves and sometimes look for days before locating the caterpillar. And what a caterpillar. All the pictures I have seen do not do it justice. Sort of looking at a calendar picture of the Grand Canyon and thinking that you won't gasp when you see the real thing. The caterpillar has rows of "lights" down the side, and pale blue oval "windows" on the lower part of each segment. Colored hairs are borne down the sides, one color along the top and a different color along the bottom, two tufts of each color per segment, one on each side. The background itself is a plastic blue, looking as fake as anything. The first time I saw one, I was sure it was a cheap 'Made in China' worm. The colors are so unnatural, it can't possible be real.
Thank you all for your help!! I definately won't spray the tree, then! This is a fairly newly planted laurel oak and I was afraid some kind of bad bug may have infected it, but these are wonderful!
I have seen the caterpillars for the hawk and hummingbird moths as they devour my daturas and brugs, but I never saw even one of these on the tree - and there had to be at least 7 because there are that many cocoons! very cool!
I've never seen one of these moths, either - do they prefer any specific type of nectar plants?
onalee - these moths do not feed as adults - they don't have any mouth or digestive system. They're nocturnal - they will spend their time trying to find a mate. It's fairly easy to tell the male and female moths apart. The females will have fat bodies (filled with eggs) and short antennae. The males will have thinner bodies and long, feathery antennae. The females emit pheromones that attract the males (that's what they use those antennae for). Once a male finds a female, they mate, the female lays her eggs, and both of the moths will die soon after.
The hawkmoths are different - they do feed as adults and live much longer. You're right, their larvae can really defoliate brugs and dats. I don't feel too bad about squashing the hornworms - I figure there are plenty of tomatoes around to keep the population going.