Bees in the pumpkin patch

Squash bee Peponapis pruinosa on a male flower

I don’t grow pumpkins or squash. But I have been visiting a couple of farms searching for an industrious little native bee, capable of pollinating their huge, bright yellow flowers with great efficiency. It is known as the squash bee, and it specializes on flowers of the cucurbit family: pumpkin, squash, zucchini, etc. Honey bees, bumble bees, and several types of halictid bees also visit the flowers, but none is as skilled as this specialist bee.

Squash bee Peponapis pruinosa on a female flower

I am collecting these pollinators to help a researcher at Cornell University who is studying them, gathering data throughout the country. There are two types of squash bees. The one we are interested in goes by the scientific name of Peponapis pruinosa. The scientific name is very descriptive, Peponapis means squash bee; pruinosa means covered with hoar-frost, which refers to the soft fuzz coating its thorax. It is about the same size as a honey bee and of similar coloration, but when you have been looking at them for a while, you have no trouble telling them apart.

The squash bee has abdominal stripes a little more pronounced than those of a honey bee, and the end of the abdomen is a little pointier. The back legs look quite different. Squash bees have hairy combs to carry pollen; honey bees have baskets, a flattened area surrounded by strong bristles. You can also tell them apart by their behavior: squash bees are all business. They waste no time, diligently going from flower to flower. Honey bees and bumble bees are inclined to dilly-dallying; all and all, they don’t visit or pollinate as many flowers.

Pumpkin patch

At times, it has been a frustrating search. I finally managed to gather a satisfactory number of bees; but there were days in which I came home empty handed, or nearly so. Probably the reason is that the farms that I visit are close to the suburbs where I live. One member of the team tells me that other pumpkin patches, located in rural areas, are full of busy squash bees during this season. It would seem that the suburban landscape, so impoverished on native trees and shrubs, fails to provide the habitat needed by squash bees.

It is worth remembering that squash bees and cucurbit plants are long-term partners. They have been fine tuning their relationship for millions of years, long before Europeans brought honey bees to this continent. For a long time, farmers have relied solely on that jack-of-all-trades, the domestic bee, for all pollination. They are finally developing a new respect for these specialist bees.

I hope that this research contributes to the appreciation of these native bees, their value to crops, and the importance of natural surroundings to ensure their welfare.

Photos by Beatriz Moisset

© 2011, Beatriz Moisset. All rights reserved. This article is the property of Native Plants and Wildlife Gardens. If you are reading this at another site, please report that to us

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    About Beatriz Moisset

    Born in Argentina and a resident of the United States for about forty years. A biologist by profession and a photographer and painter by avocation. I finally found the way to combine all these different interests in one single package when I became interested in pollinators. I have been photographing and painting them and studying their biology and ecology and I probably could spend the rest of my life doing so because the subject is endlessly fascinating and of tremendous esthetic, ecological and economic importance. Author, with Steven Buchman, of Bee Basics: An Introduction to Native Bees


    1. Donna@ Gardens Eye View says:

      Fascinating and maybe one reason in my wild but suburban garden the pumpkins flowered but were not pollinated…I had planned to learn more about this process and who were the pollinators..thx for starting my education on this topic. I am determined to have pumpkins next year.
      Donna@ Gardens Eye View recently posted..Play

      • Beatriz Moisset says:

        Thanks Donna. I hope that you have luck with your pumpkin patch next year. Make sure that you have several plants and let us hope that some neighbors have a few more. This would help the bees find enough food for their needs.
        Beatriz Moisset recently posted..Bees and vitamins

    2. Sue Sweeney says:

      Wow! Very informative article and, please, please keep up the good work!

    3. Hal Mann says:

      Thanks Beatriz,

      As a recent convert to the use/need for native plants, I’ve been skeptical as I struggle with the claims of my new found native plant friends. I’ve wondered how the little bees I see flitting about my new native garden beds could possibly be more effective pollinators than the massive, commercialized, European Honey bee. This introduction to the Squash bee helps me along this journey of discovery and conversion. Now I’ve got another book to find and read. Thanks.
      Hal Mann recently posted..Oh Happy Day

      • Beatriz Moisset says:

        Thanks Hal. There are a number of other crops that do better when pollinated by native bees; blueberries and cranberries come to mind. As for tomatoes, egg plants, peppers, and other members of the potato family: forget about honey bees; they never figured out how to perform buzz pollination. Native bees and bumble bees are real pros at that.
        Honey bees are at their best when pollinating some imported crops such as many fruit trees, peaches, plums, apples, etc.
        Beatriz Moisset recently posted..Bees and vitamins

    4. UrsulaV says:

      A friend of mine in Alaska is suffering from lack of this fellow this year, owing to a brutal late-season cold snap, and has to hand-pollinate her zucchini. You only have to do that once before you develop a healthy respect for the squash bee!

    5. Maru D says:

      Sra. Beatriz Moisset que interesante es el estudio que aquí nos ha compartido, me hace sentir mucha nostalgia de las salidas a terreno a observar diferentes insectos y plantas que hacíamos cuando era jóven.
      Muchas gracias
      (recién veo su biografía al comienzo de esta página y encontré esta dirección shared en grupos de facebook a los cuales me he incorporado porque son relacionados y como ahora se que usted nació en Argentina, le puedo escribir en castellano)
      Tuve zapallos plantados y preciosos en mi jardín sin producir frutos el año pasado y quisiera saber que diámetro y profundidad necesitan tener los túneles que usan estas abejitas squash para fabricarlos para el próximo año, por el momento tengo una casita con cinco nidos de abejas mason que limpiar y cuidar este Invierno y tuve abejorras viviendo hasta hace unos pocos días en una casa para pajaritos chikadees que colgué en un árbol, eso si que fue una enorme y agradable sorpresa, recuerdo que cuando fueron mostradas las fotografías de la casita en Native Bee Nest Site a Usted le agradaron.
      Que tenga un buen día!

      • Beatriz Moisset says:

        It is a pleasure to see that this blog also reaches some non-English speakers. I will answer your questions in Spanish by e-mail; but there are a couple of things that I want to say here.
        It is great that you are raising mason bees. They need the kind of artificial housing that we provide because we have destroyed their natural housing places, such as old or dead trees with beetle holes. The squash bee is another story. They dig holes in the soil, usually near the pumpkin plants themselves. They don’t need our help in that respect; they do it quite well by themselves. But what they really need is soil free from pesticides (herbicides and insecticides).
        Of the two pumpkin patches I visit one uses no pesticides. They resort to black plastic mulch out of necessity otherwise the weeds would take over. I found a good number of squash bees there despite the plastic. The other farm looks very clean from weeds and insect pests, no black plastic. I only found two or three squash bees. Are pesticides responsible for such big difference? I can’t tell for sure. I plan to check with other members of this project; a single observation doesn’t prove anything but it is suggestive and it matches numerous other studies.
        Beatriz Moisset recently posted..Bees and vitamins

    6. Tricia says:

      My husband and I created a number of new flower and vegetable beds this year, using organic methods for creation and cultivation and set up to encourage beneficial fauna of all kinds. I had no idea how fascinating the “critters” could be — sometimes I think I’m more interested in them than the plants! I came across this post through Pollination Station on Facebook about squash bees and was very excited to find I might have some in my own squash! I did a post on them a few weeks ago on my own blog ( but even now looking at the pictures, I can’t quite tell if I have real squash bees. I did notice their “businesslike” attitude, so I think they might be. Could you help?

      Now it’s off to explore more of your blog! Thanks!
      Tricia recently posted..A Monarch Has Graced Our Garden

      • Gloria says:

        Tricia, that certainly looks like squash bees to me. The rusty area between the head and abdomen helps ID, as it is more golden on a honey bee. Like Beatriz said once you see them a few times the differences stand out clearly. Good pictures on your blog of the squash bees.

      • Beatriz Moisset says:

        I agree with Gloria, your bees look like squash bees. I am envious of the excellent photos on your blog.
        Beatriz Moisset recently posted..Bees and vitamins

        • Tricia says:

          Gloria and Beatriz: Thanks for the compliments! The garden has been a huge boost for us in so many ways, and the photos have been one of the fun parts. They serve as a garden journal as well.

          I’m so excited about the squash bees! I didn’t realize they built nests in the ground — should I worry about that?

          It makes me want to go out and find some more exotic things! I was actually on the hunt for a nine-spot ladybug in my vine-teepee ladybug nursery (or aphid factory, depending on your view) but Irene got it. I wonder what else might be out there!
          Tricia recently posted..Caterpillar/Chrysalis Update

    7. Gloria says:

      Beatriz, we have squash bees here in Chicago. I find them very early in the morning or sometimes later in the day a couple of males will just hang out in a closing bloom. We grow some sort of summer or winter squash and even gourds on occasion.
      Since the squash bee builds a nest in the ground we are careful to leave the soil as undisturbed as possible in much of the garden. But I am always afraid they are right in the bed with the squash. So we built a couple of hugekulture beds and are cutting off stems leaving roots in the ground. We also noticed a lot more predator beetles and for the first year there was no problem with squash borer or squash bug. Need a couple more beds for rotation and a few years to see what occurs over time but for this year we have more butternut squash than I know what to do with and just one cooked yesterday gave us three cups of mashed squash for pumpkin(actually squash) bars. yummy!
      Gloria recently posted..Harvesting seed.

      • Beatriz Moisset says:

        Gloria, all this is very interesting. It sounds like you are doing everything right; I wish you luck with your patch and your bees.
        Beatriz Moisset recently posted..Bees and vitamins

    8. Kerri says:

      I didn’t know that’s what a pumpkin patch looked like! I’ve never been to one even though I love pumpkins. Never heard of a squash bee either. I thought all bees were as busy as one another. Never knew that regular bees could dilly-dally! It’s kind of cute!
      Kerri recently posted..John Boats

    9. Maru D says:

      Thank you for your lovely answer in spanish !
      I will keep coming back here to learn more !
      Muchas gracias!



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