THE DIGGER WASP
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fading at either end. This larva pupated without making a cocoon. The cocoons were not clean and had the remains of flies, sometimes whole flies adhering to them. It would thus appear that the cells were stocked with more prey than was required by the issuing larva to reach its pupation. Three cocoons were of a light brown colour, and were made of a tough paper-like substance, each measured 11 mm. in length, another was 8 mm. in length and was at first translucent white. After two days it changed to an obscure greyish colour and the pupa became invisible, and turned eventually to a light brown.
THE
PREY
The following species of diptera were taken from the wasps upon their arrival at the nest holes. SYRPHIDAE. Syrphus luriger (Mg.), Syrphus balteatus (Deg.), Catabomba pyrastri (L.). CALLIPHORIDAE. Sarcophaga carnaria (L.), Calliphora erythrocephala (Mg.). MUSCIDAE. Orthellia cornicina (F.), Dasyphora cyanella (Mg.), Lyperosia irritans (L.), Phaonia erratica (Fall.), Fannia fusula (Fall.), Polietes lardaria (F.), Mydaea scutellaris R-D.
A DESTROYER OF NESTS
In August two nests, each made by a single wasp, were marked for the purpose of collecting some cocoons at a later date. DĂźring the last week of October these two nests were opened when, to my surprise, they were found to have been robbed of their contents; only dust-like portions of flies and wood debris remained. Both the burrows and cells were infested with wood-lice, Oniscus asellus Linn. So well had they feasted that not a particle of any cocoon remained.
A TROUBLESOME
PARASITE
A species of fly was continually loitering around, but did not enter the nest holes. It moved about upon the wood and when it found a nest hole it moved leisurely around, occasionally peering in. These movements lasted for a few minutes before it moved on again, only occasionally taking a short flight and returning to almost the same spot. It appeared ferocious towards all other flies and attacked and drove them off at every approach. Only once was one observed to place an egg at the edge of an entrance hole about 2 mm. up the side.