88 
The adult is to be found on vegetation and on flowers in August 
and September. It is nearly as large as the common house-fly, but 
unlike the latter it is covered with erect, yellow, fur-like hair which 
gives it a look more like that of a bee than of a fly, and hence it has 
received the common name of bee-fly (Fig..19). The pupa, which has 
been described in detail by J. R. Malloch (47), is fully exposed and 
not enclosed within the last larval skin as are muscoid Diptera such as 
the house-fly, and it superficially resembles a small asilid pupa. 
At Galena, Ill., September 22, 1917, this fly was very abundant on 
the flowers of common roadside Helianthus, and a spider (Phidippus 
audax Hentz, det. C. R. Shoemaker) was seen to capture one of the flies 
as the latter alighted on the flowers. 
Harrworms (MesrmirHipar) 
Among the several thousand grubs reared at the Lafayette Labora- 
tory but four have shown parasitism by hairworms. These worms are 
specifically indeterminable, from our material, but belong to the genus 
Mermis, and apparently we have two species: one from grubs collected 
at Pensacola, Fla., by R. N. Wilson, and the other from grubs collected 
at Oakland, Md., by W. E. Pennington. The Florida grubs, collected 
March 1, 1915, were received at Lafayette March 3, and placed in indi- 
vidual 1-ounce tin boxes. March 16 one grub was dead and found to 
be infested with Mermis, and ten days later a second dead and blackened 
grub was noticed, and Mermis infestation was found to be the cause of 
its death. The worms were comparatively small, measuring about 6 
inches in length, and several occurred in each grub. In the second case 
mentioned, one grub among a lot collected at Oakland, Md., November 
10, 1915, and received at Lafayette a few days later, was found dead 
November 15 and infested with two worms of the genus Mermis. These 
were of cream-yellow color and noticeably larger than those infesting 
the Florida grubs, measuring 11.3 and 12.5 inches in length respectively 
(Pl. XI, Fig. 45). Dr. Henry Fox, of the Bureau of Entomology, also 
reared a mermithid from a Phyllophaga grub, obtained at Tappahannock, 
Va., May 1, 1915, the dead grub and worm being noticed July 13 of the 
same year. More recently (October 1, 1917), among a collection of 
white-grubs made by Mr. C. F. Turner at Lexington, Mich., September 
26, 1917, we found one live grub infested with these worms, which were 
visible through the integument of the dorsum of the last abdominal 
segment. These were photographed (see Pl. XI, Fig. 43, 44) and the 
live specimens were sent to Dr. N. A. Cobb, who determined the parasite 
as a mermithid. 
According to published observations Mermis has been recorded 
from a large number of insect hosts, and we have ourselves frequently 
obtained it from cutworms. The worms, on becoming mature, leave the 
host, their maturity being usually coincident with the death of the host, 
and remain in the soil probably for several months in a semi-quiescent 
condition, during which period the sexual organs are developed. Mois- 
