2o8 Marvels of Insect Life. 



to discover whether the pellagra parasite with which it inoculates man passes part 

 of its developmental history in such hosts. 



One species that occurs in the southern part of the United States, where it 

 is known as the buffalo-gnat, is in evidence every year, but at irregular and distant 

 intervals it appears in almost incredible swarms. Stock-owners then endeavour 

 to keep it away by means of smoke. The animals when attacked by large numbers 

 of the flies are driven frantic, and seek to elude their tormentors by rolling in the 

 dust or rushing about. They are at such times almost covered by flies, and as the 

 result of their bites an inflammatory fever with rapid pulse is set up, and the animal 

 dies of cramps or convulsions, " when the skin of the entire body will be found to 

 be covered with numerous small ulcers." Mosquitoes and midges become trouble- 

 some towards night ; but the flies under notice attack beasts, birds and men in full 

 sunlight. There is one case on record of a man being so badly bitten that his death 

 was speedy. A smaller American species known as the turkey-gnat is especially 

 annoying to poultry, particularly turkeys, which they attack in the bare regions 

 about the head, in the ears, eyes, etc., often killing them in great numbers. 



Sand- Wasps. 



Among the many tvpes of solitary- 

 wasps, the sand-wasps ^ stand out 

 distinctly on account of their long, 

 slender bodies, of \\'hich the hinder 

 section is connected to the fore-body 

 b}' a very long, tapering stalk. One 

 species, the red-banded sand-wasp, ^ 

 may be seen busily engaged at work 

 Photo by] [E.K.Pcane. at almost any sandbank. It is an 



Pellagra-Fly. Insect about three-quarters of an inch 



One of the small black flies that are alleged to carry the germs of . _ - 



pellagra to the human subject. The expanse of the two wings in \x\ length Cntirelv black SaVC for a 



these flies is very great, the depth from front to back being exceptional. o ' „ ^ ' 



The actual width across the expanded wings is nine millimetres. band of rcd wlllch includcS half of thc 



hind-body and a third of the connecting stalk. There is a distinct neck 

 between the fore-body and the head ; and the legs are armed with 

 spines and bristles to aid in digging. The invariable food selected by these 

 sand-wasps for provisioning their cells is a caterpillar or caterpillars, according 

 to species, for each kind seems to have its own favourite species of caterpillar for 

 the purpose. There are many species of sand-wasps in different parts of the world, 

 but their habits arc so much ahke that they can be described in general. 



In recent years we have had accounts of the sand-wasps' activities from Fabre 

 and Marchal ; but as long ago as the summer of 1667 our countryman, John Ray, 

 and his friend Willughby were observing it, and Ray has told us in liis History of 

 Insects what they saw. The sand-wasp was dragging along a green caterpillar 

 three times its own size. When it had dragged this huge load along a distance 

 of about fifteen feet, it came to a hole })reviously dug in the sand, and left the 

 caterpillar beside it whilst it set to work to remove a pellet of earth that blocked 

 the mouth of the shaft. The wasp descended into the cavity, but soon reappeared 



1 Sphegides " .Xmniophila sabulosa. 



