Guest entomologist blog

Many people have a way of marking the beginning of spring, and usually the first sign is noticed in the garden, the plot of green space closest to our brick and concrete abodes. For some it is the first daffodil, or the first swallow flying overhead, or the sight of birds collecting nesting material. In these days of calendars, atomic clocks and “accurate” weather reporting, the arrival of spring is one of the few things that people still turn to nature to decide.

As an entomologist, I tend to notice the smaller things and notice them in stages. For me the first sure sign of spring approaching is the appearance of the flowers on what is variously known as Sallow, Goat Willow or Pussy Willow. Without fail, these attract the first flies of the year, usually including the honey-bee mimicking Drone-fly and the elongate and stripy Marmalade hoverfly, both common sights in the garden from spring onwards and two species that, unusually for hoverflies, hibernate, so require an abundant early nectar source upon awakening.
These are shortly followed by the appearance of the first bumblebee, always a queen at this time of the year, and usually a huge hulking beast of a bee. This early in the year they need to go about constructing nests and feeding the first brood of worker larvae, so at this difficult time of year they appreciate as much floral abundance as possible. They too also visit Goat Willow flowers, but also early-flowering Heathers, Peas, Crocuses, Primroses, Comfrey and Bugle. At a time when bees are disappearing, the conservation importance of early-flowering plants in the garden cannot be overstated as these help to set up the nests for the rest of the year.
One particular species, the brown Common Carder Bee, can be seen gathering moss on lawns at this time of year to make its nest. Later on in the spring it is fascinating to watch the workers working together in collecting and untangling the moss and transporting it to the nest. The next bee to show up is very common, but frequently overlooked by the gardener.
It has the unfortunate common name of the Hairy-footed Flower Bee, but I much prefer its much more elegant Latin name, Anthophora plumipes. This is a large solitary bee, nesting in holes in walls. The moderate-sized gingery male is usually the first to appear around mid-March, closely followed by the much larger black female. Both are particularly fond of Lungwort, and this is where the first few are usually seen, but also visit Comfrey and similar plants. Their skill in hovering and the speed they travel between flowers is simply incredible given that it is often still cold at that time of year.
The next on the scene are often first noticed by the appearance of small holes surrounded by volcano-like mounds of soil in the lawn, particularly if there are any bare patches. These are caused by the mining bees which, like Anthophora, are solitary, although often many nests are found in a small area. I have particular fondness for two species that be found in gardens, the dark-ginger, furry and friendly-looking Tawny Mining Bee and the black and grey Ashy Mining Bee. Both are non-aggressive and have a very weak sting, and are excellent garden pollinators, particularly of current bushes and fruit trees.

But, even though by this time the garden has begun to come alive with insects, flowers and nesting birds, spring has not yet sprung for me. The temperature is still cold and the weather still very unpredictable. For me it comes when I see the first of a creature that needs warmth to go about its daily business.
For me, the start of spring proper is when I see my first bee-fly. These are curious insects, flies that closely resemble bees, frequently seen hovering, but darting away when disturbed faster than most garden insects. Most noticeable is their long proboscis, which they use to get nectar from tubular flowers such as Primroses, Cowslips and Violets. When close by they emit a tiny whining noise. Their larvae are parasitic on ground nesting bees such as the two mentioned above, but they do not pose a big threat to them. The females can often be seen “dusting” in dry bare earth, the reason for this being a bit of a mystery. They can also be seen flicking their tiny eggs onto short grass and bare earth, not necessarily where the bees are nesting, but where they are likely to be nesting, which gets them over the messy business of encountering angry bees if they were to search more carefully.
Two species are found in gardens, the Dark-edged Bee-fly, with a long dark bar across the top of the wings, and the much rarer Dotted Bee-fly, with lots of small dots on the otherwise clear wings. They cannot even walk below 12°C and need it to be about 17°C. When the temperature is colder, they will rest under a leaf and remain immobile for a week or more. Sometimes, I think, nature has got things just right! So when I see the first bee-fly, I know it’s time to throw away the winter sweater, dig out my shorts, sit outside with a good book and look forward to the summer.