What's on the Ivy.

[nomad]

One of the best places to watch insects in the autumn is at the ivy flowers and the buds remain sticky with pollen after they disappear for a while before the fruit forms. Sometimes the ivy will be a buzz with insects, many will visit for the rich nectar and these attract predators, who will also take a pit stop from their hunting to have a nectar fill. One of the most noticeable  is the large Hornet Vespa crabro, which will after a successful hunt, will hang on one leg to dismember a victim and take the protein rich part back to their nests.  Here are a few images of them and also of the smaller but beautiful gall wasp, Ormyrus nitidulus, the one shown here is a female, the second from bottom image is it feeding with an ivy bee, Colletes hederae, which only turned up in Britain in 2001 and is now spreading northwards, also shown in the last image. All the photos were taken on the same patch of ivy.

[mcheki]

Interesting topic and excellent pictures as always.

[nomad]

If the hornets are the apex predators, there are many common Vespula wasps on the hunt among the ivy and from the image above you can see one has fallen victim to the much larger Vespa crabro. The brightly coloured but much smaller Ectemnius wasps (image 1) also hunt among the ivy but with a different strategy to the others, they are ambush predators with large mandibles, waiting on leaves for their victims to approach, often taking hoverflies who are often as large as themselves, flying with them back to stock their solitary nests, often a hole in a bank that will be a food source for when the larva hatch. Many pollen feeding Diptera mimic the stinging bees and wasps. Leopoldius signatus from the Conopidae family of Diptera, with the descriptive vernacular name of Ivy-leaved Bee Grabber is a small but good wasp mimic (images 2 & 3). L. signatus is a decidedly local and fairly uncommon species with a sporadic distribution in England and Wales that does occasionally take pit stops for nectar, they are usually very active among the ivy, the males searching for the females, who are on the lookout for an unsuspecting victim, a bee, not as prey but as a storage facility in which to lay their eggs. The female grabs the bee in mid-air and inserts her ovipositor into the bee's abdomen, when the eggs finally hatch, the bee is doomed as the parasitic larva fill up the abdomen in 10-12 days.

Many species of hoverfly of the Syrphidae family also are good mimics, they visit the ivy for pollen that include the Hornet mimic Volucella inanis (image 4) and wasp mimics such as the common Syrphus ribesii (image 5). Often the most common hoverflies at the ivy are the drone flies that mimic honey bees, there are several British species including Eristalis tentax, individuals of thi species hibernate through the winter, appearing in the spring  (image 6). All photos, England, 2018.

1. Ectemnius species.



2 & 3. Leopoldius signatus. Top male, bottom female.



4. Volucella inanis female.



5. Syrphus ribesii female with extended abdomen full of eggs.



6. Eristalis Tentax female.