528 



NATURAL HISTORY OF ARTHROPODS. 



FIG. 654. Pompilius formosus, tarantula-killer. 



lapse of several years, the spiders were still limber and showed no signs of decomposi- 

 tion. This species has but one annual generation, and the adults issue in June. They 



feed by preference from the blos- 

 soms of Asclepias quadrifolia, 

 which blooms in Texas through- 



O 



out the summer. Pompilius 

 natalensis is one of the most 

 beautiful species of this genus. 

 Its head and thorax are velvety 

 black, antennae yellow, fore legs 

 and tip of abdomen brilliant 

 red, and wings gold-yellow. In 

 Natal it is almost domestic, fly- 

 ing in and out of the houses, 

 capturing the house-spiders, and 

 making its nests before the door 

 or under the veranda. 



Agenia and Priocnemis are 

 allied genera. The females of 

 the former build little barrel 

 shaped oells of clay, which may 

 be found under the bark of trees, in the crevices of walls, and sometimes in sand bur- 

 rows. Agenia bo/>il>;/<-iita makes its cells under prostrate logs in South Illinois, while 

 the allied A. subcorticalis preferably selects a 

 position under the loosened bark of standing 

 trees. Species of the parasitic genera Ptero- 

 malus and Mesostenus have been bred from 

 these cells by Walsh. 



The family SPHEGID^E is a group of large 

 extent and of considerable diversity of char- 

 acter. It includes the eight sub-families, 

 Larrinae, Spheginae, Mellininae, Bembecinae, 

 Nyssoninae, Philanthinae, Pemphredoninae, and 

 Crabroninse, nearly all of which have been con- 

 sidered at one time or another as having family rank. As already stated, the Sphegida? 

 are separated from the rest of the digger wasps by the pronotum, which does not ex- 

 tend to the base of the wings. 



The sub-family Larrinae is of small extent, and is composed of insects of small size, 

 rather slender form, ovoid-conical abdomen, and with a single spine at the base of the 

 middle tibia?. The mandibles are notched exteriorly near base, and the labrum is 

 concealed. Although the European and North American species of Larrada and 

 Tachytes are said to be borrowers in the ground, particularly in sandy soil, a Brazilian 

 species of Larrada is said by Mr. H. W. Bates to form for itself cells composed 

 apparently of the scrapings of the woolly texture of plants, resembling bits of sponge 

 or German tinder, and attached to leaves. The anterior tarsi of this species differ 

 decidedly from those of the burrowing species and indicate well the difference in habit. 

 Tachytes aurulentus frequents the blossoms of Asclepias, and is often found with the 

 pollen masses attached to the hairs of its tarsi. The tarsus figured by Packard in his 



FIG. 655. Agenia bombi/c'uia and cell. 



