There is no genus of insects whose habits are more formidable, 

 or whose economy is more extraordinary, than the (Estridce. 



It has been on a former occasion remarked, that our GEstri 

 were unknown to the ancients, and that the " flying plague " 

 mentioned by Virgil was a Tahanus (Plate 78), an insect as 

 remarkable for the perfect organization of its instrumenta ci- 

 haria.^ as (Estrus is forJ;he absence of those organs. 



Although the seeds of inquiry were first sown by Malpighi, 

 Vallisneri, Reaumur, and De Geer, Linneeus and cotemporary 

 writers were but imperfectly acquainted with this family ; and 

 it was to the ingenious and masterly investigations of our own 

 countryman Mr. Bracy Clark that we are put in complete pos- 

 session of the habits and economy of the different species, and 

 enabled to examine them scientifically. The European (Es- 

 trida have been sepai'ated by Dr. Leach into 2 genera, in 

 which he has been followed by the most learned Dipterist of 

 the day. The genus QLstrus is distinguished from Gastero- 

 philus by the economy of its larvae and the nerves of the wings, 

 and comprises 4 British insects. 



1. CEstrus Ovis Linn. — Clark's Essay, tab. 2.f. 16. to 20. 



— Do7i. Brit. his. v. 16. pi. 550. 



2. Bovis Linn. — Clark, tab, 2.J\ 1. to 10. 



3. Ericetorum Leach. 



4. pictus Meig. — Nob. 



The larvae of CE. Ovis live in the frontal cavities of the 

 sheep, change to chrysalides about June, and in August 

 the male flies are found not unfrequently sticking to pales 

 and walls in the neighbourhood of sheep pastures. 



The larvae of 6E. Bovis, called Warbles, Wormals, &c., 

 live under the hides of oxen and cows, change to chrysalides 

 about the end of June or later, and the fly appears the middle 

 of August. 



CE. Ericetorum is considered as a variety only of (E. Bovis 

 upon the Continent. 



We cannot but congratulate our readers on being able to 

 present them with another species of this singular family, es- 

 pecially as it is a fine and handsome insect of great rarity and 

 has never before been figured : as a British insect it is unique, 

 a single specimen having been taken by Mr. Samouelle in the 

 New Forest at Burley Heath, 12th of June, 1823. Of its habits 

 we know nothing ; but it is not improbable that it is attached 

 to the deer, and lives in the larva state probably in the frontal 

 cavities of the head of that animal. 



The plant is Valeriana dentata (Oval-fruited Corn Salad). 



