The genus of Grass-carrying wasps, or Isodontia, contains more than 60 species worldwide with about 6 species in northeastern North America. Isodontia belongs to one of my favourite wasp families, Sphecidae, or the thread-waisted wasps.
They have these fabulous petiolated (thin, long stem) waists.
The Sphecidae used to have their own superfamily, Sphecoidea, which also used to include Crabronidae (which I posted about yesterday). Sphecidae and Crabronidae are now included in the Apoidea, the superfamily of bees.
It’s a little bit strange, and a little bit confusing that this should be so, given that the Crabronids seem to be ancestral to the bees. And there remains no convenient grouping within Apoidea to separate the bees from the “sphecoid wasps”.
Instead, many bee specialists have commandeered the term sensu lato “Anthophila” (“flower loving”) for the bee families within Apoidea, and they are very jealous of the term indeed. In spite of the attempts of Lepidopterists to apply the term to butterflies and moths that visit flowers, or other entomologists which casually use the term to describe any flower-visiting insect, bee biologists demand that Anthophila be restricted to a category somewhere between superfamily and family among the Apoidea.
But if you have spent any significant amount of time watching flowers and the things that visit them, you will have noticed that the bees are not the only visitors. Indeed, butterflies, moths, flies, flea beetles, soldier beetles, and especially wasps are equally common.
What is the potential for these other insects to act as pollinators (that is, to actually move pollen from one flower to another)? Well, the Sphecids lack the branched body hairs of the “Anthophila”, and therefore pollen does not quite stick to them as effectively. They also lack the pollen collecting apparati (scopa) of the bees.
So you can see that pollen definitely seems to cling to bees more readily.
But it is hard for me to imagine that other insects are completely useless in pollination. It’s just that we have yet to quantify what effect, if any, they have on the seed set and fecundity of the plants that they visit.