Pristophora abbreviata-California pear sawfly info wanted

We're not big advocates of pest control at BugGuide.

This site is more about appreciating the little critters all around us than exterminating them. However, a web search can turn up guidelines on how severe the problem should be before spraying is required, like this University of California IPM. It's really aimed at commercial growers, though. Only you can decide how much damage to your tree you will tolerate. I have read that one third of a bean plant's foliage can be lost before bean production is reduced, but I don't know what the numbers are for pears.
Moreover, from your description it's not entirely clear that California Pear Sawfly is the problem - the larvae are supposed to eat holes in leaves, rather like leafcutter bees - I don't see any reference to rolling. See picture here. If this is your pest, it only has one generation per year so the damage will be at its worst right around now. The rolled up leaves with silk on them might well be unrelated - spiders, for instance, often do this. There would be no threat to neighboring trees from sawflies, as they are host-specific.
I would advise that you not apply any chemical control without knowing for sure what the pest is. I have a friend who destroyed caterpillars of Giant Swallowtail butterflies on her citrus for years until she found out what they were, and that they were really doing no more than minor cosmetic damage.

… Hannah Nendick-Mason, 12 May, 2006 - 7:11am

Thanks for replying

That's exactly why I posted here. I had found both of those posts, which is how I verified my ID. A call to my extension office suggested this sawfly or some kind of leafroller, based on my description. I had found both of those posts, which is how I verified my ID. Those websites you refered me to only addresses the larvae eating leaves, and controls for them. Since I only have one tree, it is easy to monitor. I did notice no damage on other surrounding plants. I have no idea what lifestyle the adults have. For all I know, they could be an important pollinator.

Thanx for telling me that it is only one generation. That helps a lot. I didn't want to let it go, and see my tree become entirely defoliated. Do you know a good source of info on their life history? My car died in November, and I have since then decided not to replace it. It is hard to give up the idea of going to the mountains or the beach, either less than two hours by car. I have decided to study whatever I can close to home.

I did remove some of these critters this morning by shaking them onto a white bedspread and moving them into the driveway. I found a nice spider in the grass. So I brought her inside to get a closer look at her later. A very pale yellow crab shaped spider.

I was hoping my little songbirds would visit me and eat some more. I do think that the curling is a different beastie. I also saw some damage that looks like the mite damage I see on my grape leaves. Both of these are really minor compared to the chomping of the sawfly larvae they have damaged between 5 and 10% of the leaves.

This morning, I saw one larva dropping down a silk. Was he going to pupate? I read somewhere that sawflies pupate in the soil, I think it was in my Peterson's feild guide.

I don't know much about insects. Is the family usually enough to tell a person about the insect's lifestyle?

Any guidance is appreciated.

Mary

… plantluvver, 13 May, 2006 - 1:23pm

You're right, they pupate in the ground

see this website. I don't have any books that provide more detailed information. I'm sure they perform some pollination, since the adults feed on pollen and nectar (see our guide page), though the most significant pollinators are usually bees, I think. As you've already noticed, they are food for birds and thus have a role to play in the food web/ecosystem. I'm glad you're inclined to observe them rather than destroy. :)
By the way, if you could get some pictures of them, it would be a new species for us.
In answer to your last question, yes the family (and, more to the point, genus and species) can tell you a lot about the lifestyle. For instance, sawflies are usually host-specific, that is they only eat one kind of plant and will not move to other kinds of plants. Unlike this one, some sawflies have more than one generation per year, which would potentially cause more damage.
Just by browsing around the pages of this website you'll no doubt find a lot of interesting and useful information about what's in your back yard. I hope you have plenty of time - it can be addictive!

… Hannah Nendick-Mason, 14 May, 2006 - 5:42am

Thanks for being my bugbuddy !

I did not find that page in my search, so thank you for the reference.
My question about families was just to judge how much I can rely on related species descriptions, if I don't find info for a species, and whether misidentifying a critter will lead me to incorrect conclusions about it. My Peterson guide only goes to family, and is actually useless, since only adults are pictured. My id is based on a mug shot, and I know that a biologist would use a dichotomus key, and may need to count little body parts under a microscope. (Though, now that I've thought about it, an ID by picture could even put me in the wrong family.)

Unfortunately, I don't own a camera. I am so glad to have you as a bugbuddy, my boyfreind's reaction was to suggest that I buy something to spray on them. Even after I told him I was hoping the birds would eat them, he thought I was batty, and silly to wait for the birds. Made me physically nauseous to think about how many birds are poisoned by people wanting a quick fix. I wonder how many gardeners even realize that most insects have quite different forms and lifesyles as adults? I thought this was common knowledge, that catepillars turn into butterflies, but my neighbor once said something to me that made me think this was news to her.

I found it difficult enough just to hand pick them and then shake then out of the tree. They are such a lovely apple green color, and I find their habit of sitting on the rim of the hole just charming and, shall I say it? Cute as a bug!

I would like to know more about the role they play in pollination. My tree has bloomed well for a few years now. But it has set at most 3 pears. This year there are more than three fruit set, thogh I don't know how many. I had meant to observe my tree more closely this spring to see if anyone was pollinating it, but I didn't. The timing shown on this new webpage shows that these guys might be my little helpers, and being host specific, they would be nearby to lay their eggs. I am glad I am spending the time on them. Perhaps the next time I am at school (Portland State University, Math) I will look for some journal articles about them.

I am surprised at my reaction to the yellow jackets eating them. I suddenly saw them as something other than pesky picnic crashers. And one was so absorbed in trying to hang onto his (correction, probably her) 'worm' that I had no fear of her 'attacking' me. I have a great fear of them, although I've never been stung by one (Probably, I fear them even more because of that, not knowing what to expect exactly.) Someone once told me that we have many species of yellow jackets. At the time I wasn't interested, I was only interested in destroying the nests they built under my aluminum siding in my attic window.

Mary

… plantluvver, 14 May, 2006 - 11:10am