Arthropedia - Heavenly Hogweed

Hogweed (Heracleum sphondylium) is undoubtedly one of the best umbellifers in Britain for attracting insects. It is an absolute magnet for all sorts of beetles, flies, bees and wasps.

The lovely lacy flowerhead of Hogweed in full bloom. A magnet for invertebrates, except in this instance where I’d just scared them all off!

A single Hogweed flowerhead can often be smothered in various creatures. They congregate not only to feed on the nectar and pollen produced by the multiple flowers but also to seek out a mate or to feast on the diners themselves. In fact one of the biggest drawbacks with hogweed is that it can attract so many things that you really don’t know where to look and what to focus on. So often you photograph one thing only to discover on looking at the photos afterwards that something even more exciting was also on the flowerhead but went unnoticed. You then have the dilemma of did you actually see it or not!

A variety of insects can be found on the large flowerheads of Hogweed, even when they are past their peak like this one.

Depending on the year and what part of the country you are in, Hogweed season starts off in late May or June, continues through July and August and often goes on into September. This long flowering period coincides with peak insect time so it is hardly surprising that so many things have been recorded visiting it.

Lack of focus: I was trying to photograph the sawfly but other things kept flying in and distracting me! (Fly *Musca autumnalis*, *Tenthredo* sp sawfly, *Rhagonycha fulva* beetles, *Eumerus* sp hoverfly and unidentified fly).

Hogweed can be found growing in a variety of places from roadside verges, hedgerows and woodland rides to field margins and wasteground, tolerating various soil types. Depending on where the plant is growing you will find different insects. Near woodland they will attract beetles whose larvae feed in decaying wood while in wet areas adjacent to marshes there will be specialist flies and hoverflies whose larvae have an aquatic existence.

Hogweed plants growing near a hedgerow by arable fields.

Hogweed is a native perennial (or sometimes biennial), not to be confused with the introduced Giant Hogweed (Heracleum mantegazzianum) which gets such bad press because of the compounds in its sap (which are also present in parsnips and Hogweed) that can result in severe blistering of the skin if you aren’t careful. It is a tall, rather elegant plant with large flowerheads that are made up of multiple flowers in umbels. The flowers are usually white but can also be pale pink.

A rather lovely pink flowered specimen with a bumblebee, longhorn beetle and solitary bee.

Hogweed flowerheads really are superb for all manner of insects. The large heads provide an ideal platform to settle on and the pollen and nectar is readily accessible to different types of feeding techniques. As such, a sheltered stand of these stately umbellifers is as much a magnet for the naturalist as it is to invertebrates. Hoverflies are particularly attracted to these wonderful flowers as are a whole array of beetles. Not only do the flowerheads provide food in the form of nectar and pollen, but they make an ideal platform to meet up and mate on!

The height of Hogweed is sometimes a problem: standing on tip-toe and gently bending over the flowerhead to see what, if anything, is on it is a delicate task as a sudden movement will make things fly away or deliberately fall off.

A Hogweed flowerhead is the centrepiece of plate “P is for Pollinators” in my book Arthropedia: an illustrated alphabet of invertebrates.

H is for Hoverflies

Hoverflies are a favourite group with many wildlife enthusiasts, especially those just venturing into invertebrates (usually after butterflies and dragonflies). Many are quite large and distinctive making them relatively easy to identify and they often pose nicely for photographs too. Although the larvae of hoverflies have various different lifestyles, nearly all the adults visit flowers and are therefore very important as pollinators.

Two readily identifiable hoverflies: top *Myathropa florea*, sometimes called the Batman Hoverfly from the dark pattern on the thorax and *Chrysotoxum bicinctum* below. Both are described as wasp mimics, although I think one is better at it than the other.

*Volucella bombylans* is a bumblebee mimic, seen here with a male *Bombus lucorum* to prove the point! The females actually lay their eggs in bumble nests where the larvae feed on detritus in the bottom of the nest but probably aren’t above eating the odd bee larvae or two that comes their way.

*Eristalis* hoverflies require photographs from different angles to identify to species although *E. nemorum* often gives the game away by having a rather characteristic mating behaviour with the male hovering above the female, often two or more stacked up above her, while she visits flowers.

This lovely hoverfly is *Melangyna compositarum/labiatarum* which cannot be distinguished from photographs proving that not all distinctive looking species are that easy after all.

*Anasimyia lineata* is a wetland specialist. This one was photographed at Strumpshaw Fen in Norfolk. Their larvae are known as rat-tailed maggots, living submerged in well vegetated ditches and ponds.

F is for Flies

Plenty of different species of fly can be found visiting Hogweed flowers. Amongst the ubiquitous Blue and Green Bottles and annoying non-descript jobs all sorts of pleasures await the curious observer. Depending on where the Hogweed is growing you will find more interesting species. Wetland areas for example will have soldierflies from the order Stratiomyidae whereas dry grassland areas will host various Tachinids that specialise in parasitizing the larvae of moths and other insects.

The soldierfly *Oplodontha viridula* can be found visiting Hogweed flowers in wet habitats. This is a particularly pale specimen, others are actually green on the abdomen from where they get their English name Common Green Colonel.

*Empis tessellata* is one of the ‘dance flies’ so-called from the way males congregate and dance in the air in small swarming groups to attract females. They are predators of small flies, the male even presenting one as a nuptial gift to the female prior to mating.

*Physiphora alceae* is a member of the family Ulidiidae which are collectively known as Picture-winged Flies as many species have patterned wings. The males often wave their wings about to attract females or to warn others off their territories.

Anyone who says they don’t like flies can’t have had the pleasure of encountering *Phasia hemipter*a. This large Tachinid is parasite of shieldbugs, its larvae developing in the nymphs of the host species.

*Cistogaster globosa* is another Tachinid fly and is a parasite of Bishop’s Mitre shieldbug nymphs. I’ve usually encountered this species in areas of dry grassland, especially the Norfolk Brecks.

Beetles

Hogweed attracts lots of different beetles and can often be swarming with them. In fact the soldier beetle Rhagonycha fulva can be so abundant that it is commonly known as the Hogweed Bonking Beetle.

Some of my favourite beetles are the various longhorns. The larvae of most of them feed in dead wood but the adults are frequently found on flowers, especially Hogweed, although some are nocturnal. Many of these beetles are quite large and conspicuous and while some are quite common others are extremely rare. They are all a delight to find.

*Rutpela maculata* is quite a common species of longhorn beetle with rather variable black markings on its otherwise yellow wing cases (elytra).

*Grammoptera ruficornis* is one of the smaller species. It is common and widespread and is often found on Hawthorn blossom as well as Hogweed. In my garden it visits the rose ‘Canary Bird’.

This Tobacco-coloured Longhorn (*Alosterna tabacicolor*) was found in woodland in Northamptonshire while looking for Wood White butterflies.

*Clytus arietis* is called the Wasp Beetle after its bold black and yellow markings.

Possibly my favourite longhorn beetle – *Agapanthia villosoviridescens*. They can be found visiting Hogweed flowers but more often than not are seen clambering about lower down on the stems. The larvae of this species actually develop within the stems of Hogweed and other herbaceous plants, such as thistles.

B is for Bees

Solitary bees make good use of Hogweed, especially the Andrena mining bees.

*Andrena proxima* was recently rediscovered in Norfolk (by Tim Strudwick in 2018) after an absence of over a hundred years and seems to have a strong association with Hogweed. Above is a male and below a female that was photographed with its cleptoparasite *Nomada conjungens* which I hadn’t even noticed at the time.

*Andrena chrysosceles* is called the Hawthorn Mining Bee largely because it is on the wing when the Hawthorn is out. Like many bees it is polylectic – it will collect pollen from a variety of plants, Hogweed included.

*Andrena minutula* females. There are several species of very small (or micro) *Andrena* bees that belong to the sub-genus *Micrandrena*. *A. minutula* is by far the commonest.

Even smaller than the Micrandrenas are the *Hylaeus* bees. These bees are unusual in that the females collect pollen and nectar in a crop (rather like a bird) rather than having a scopa (an array of hairs either on the leg or under the abdomen). This one is a male *Hylaeus dilatatus* which has distinctive swollen bases to the antennae which are yellow and black.

W is for Wasps

Both social and solitary wasps can be found visiting flowers. Male social wasps in particular can be found generally lounging around and fuelling up in between stints of looking for a virgin queen to mate with.

Male *Dolichovespula saxonica*, one of the social wasp species. These look very similar to our Common Wasp *Vespula vulgaris*.

Solitary wasps come in all sorts of shapes and sizes but many of them share the black and yellow livery of their social cousins. Their English names often reflect their nesting or hunting behaviour so for instance there are digger wasps and potter wasps as well as spider-hunters.

*Oxybelus uniglumis*, the Common Spiny Digger Wasp. This species preys on small flies; the female impales them on the tip of her abdomen and drags them back to her nest burrow.

*Cerceris rybyensis*, the Ornate-tailed Digger Wasp, is easily recognised by the yellow band at the front of the second abdominal segment. They provision their nest cells with solitary bees.

*Symmorphus bifasciatus* is a wetland species which preys on willow leaf beetle larvae. This one was at Strumpshaw Fen in Norfolk. Photographed next to *Rhagonycha fulva*, the famous Hogweed Bonking Beetle.

The amazing *Gasteruption jaculator* (I presume!).This improbable looking creature is a female with her seemingly outsize ovipositor which she uses to lay eggs into the nest cells of *Hylaeus* bees.

Moths

A few day-flying moths can be found visiting hogweed, including Pammene aurana whose larvae actually feed on the seeds, tucked up in a little silken retreat.

A longhorn moth *Cauchas rufimitrella* and several *Glyphipterix* (probably *G. simpliciella*, the Cocksfoot Moth).

Spiders

Where insects congregate to feed you will also find various spiders ‘hanging out’ or just lounging around to pick up a tasty meal. Misumena vatia is one of our loveliest crab spiders and a deadly predator to whatsoever comes its way, although interestingly I have never seen one take a beetle. Indeed I have seen numerous Hogweed Bonking Beetles (Rhagonycha fulva) clambering over a hogweed head and its recumbent Misumena and she hasn’t touched one of them. Perhaps the orange colour of the beetle is a warning that they are distasteful so they are left alone?

Banqueting table: a female *Misumena vatia* politely waiting for her dinner to get within reach…

Enoplognatha spiders often sit in a web under the individual flowers, tucked away in the ribs of the flower umbel waiting to ensnare the unwary. Their presence is often given away by the remains of corpses dangling below the petals.

*Enoplognatha* species usually lurk in a web under the flowers. This one has come out to deal with a small wasp that has become ensnared.

Surprise Find

You never know what might turn up when you’re out hunting for invertebrates. My particular passion is for solitary bees and that is what I am principally looking for when I venture out. All the other stuff I record is really ‘by-catch’ that either got in the way when I was looking for bees or proved a nice distraction while I was waiting for bees to show up. There are a few exceptions though that beat the bees for my attention, well for a little while anyway! One such creature was a fabulous Snakefly, a species I had never seen until this year. There are four species in Britain, all very similar and associated with trees where the larvae feed under the bark on other insect larvae. The adults prey on aphids but also eat pollen.

Other Umbellifers are Available

Hogweed is undoubtedly one of the best umbellifers when it comes to attracting insects but there are plenty of others. Wild Angelica (Angelica sylvestris) is also superb and is found in wetter habitats. It is particularly good for hoverflies. Earlier in the year Alexanders (Smyrnium olusatrum) are very good for spring species including solitary bees. On our sandy soil, Wild Carrot (Daucus carota) is excellent and we grow it in our garden. Rough Chervil (Chaerophyllum temulum) is a delicate umbellifer that is found along hedgerows. On our allotment we grow the Mediterranean herb Fennel (Foeniculum vulgare), mainly because its frothy yellow flowerheads are so good for insects. The fresh green seeds are nice to nibble on too, if you like aniseed that is. In fact there is a whole succession of different native umbellifers that come out one after the other to provide flowers throughout much of the year.

Cow Parsley (Anthriscus sylvestris) can be very prolific during the month of May but I fail to find much on it other than a few beetles, although I’ve been told that it is very good for certain hoverflies. I probably spend too much time looking at Hawthorn blossom at this time of year and fail to give Cow Parsley due attention – I must try harder!

Arthropedia – the Book

This blog is written as a companion piece to my book ‘Arthropedia: an illustrated alphabet of invertebrates’ published by Mascot Media. The book is a celebration of the rich diversity of insects, spiders and other arthropods to be found in our gardens and wild spaces.