I’m stuck on you


Braconid wasp cocoons on a tomato hornworm. © Nan at Shady Grove Farm, Kentucky.

Speaking of wasps, I just received this photo from Nan at Shady Grove Farm in Kentucky. The white things you see attached to a tomato hornworm are the pupae of a braconid wasp.

Using her ovipositor, the female braconid lays her eggs inside the body of the caterpillar. Once the eggs hatch, the larvae eat the insides of their host which, as you might imagine, is not good for the caterpillar. After the larvae mature, they eat through the skin of the caterpillar, attach themselves to the outside, and spin a cocoon. Eventually, the wasps mature and emerge as adults.

The Braconidae family is huge, containing perhaps 1700 species in North America. They are all parasitic on other insects or insect eggs. The adult wasps are small, usually less than a half-inch long.


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  • I had some of these visitors in my own garden a couple of summers ago. I picked off a dozen of the hornworms, but left the ones that had the cocoons. Since then I’ve seen exactly one hornworm on my tomatoes. I really think people who use pesticides miss half the fun of gardening.

    (By the way, believe it or not there is a species of parasitic wasp that will lay its eggs in these cocoons in order to parasitize the parasites.)

  • Anubis,

    “miss half the fun of gardening” is absolutely right. Like watching a mantis holding a stinkbug in its forelegs and munching it exactly like a hamburger.

    The longer (25 years on this land) without pesticides, the more beneficials there are from year to year.


    • Nancy,

      I’ve lived on my patch going on 20 years without pesticides, and it is amazing the amount of wildlife etc. that has decided this is a good place to be. What amazes me more, is the balance of living things. For example, mosquitoes have disappeared since the birds increased, my fruit trees produce more and bigger and nicer fruit than ever. It’ amazing what nature will do when you let it.

  • Wasps are way cool. Speaking of which, check out this photo I took of yellowjacket brood. I had assumed that yellowjackets just burrowed like ants, but they construct a whole nest down there. I also find it fascinating that rather than putting in winter stores like honeybees, they all die off except for a queen – who starts the colony from scratch in the spring. It had always seemed that there were more and more yellowjackets as the summer went along, but I’d never known why.

  • Rusty hello, I have tried to find information re the parasitic fly Chrysura refulgens on the Dutch beekeeping sites but came up with nothing. This fly is quite beautiful. She has a bright blue thorax and a bright pink abdomen. When I first saw her on top of one of my hives I only thought she was a beaut. At home I found out that this type will parasitize bees. I knew there was nothing I could or should do because my bees are situated in a nature reserve and everything has to have its chance. I had noticed though on the varroa boards there were many bee legs but they were under my strongest hive so I wasn’t terribly worried. The bees going inside were always busy and often fully laden with pollen so everything seemed fine.

    Today I needed a comb of open brood to help another small colony along so I thought I could pinch it from the strong hive. I dismantled the honey chambers and they were very poorly occupied. Further down the situation got worse and worse. I found hundreds and hundreds of dehydrated bee heads and abdomens separated from each other. Even most sad a bee front half still alive and pulling her broken back leg behind her. Part of her middle and back end were just gone. Is this the work of this parasitic fly? There was no capped brood in the whole hive but there was open brood. Do you have any ideas what this can be. There are no signs of nosema or other sicknesses and varroa mite fall is very slight. I am perplexed.

    • Lindy,

      I have no knowledge of your fly. The only time I have seen bees pulled apart like that was due to yellowjackets.