414 



how often, but feel sure they occur every year, and more than once each year, occu- 

 pying about the whole day in their flight. — [J. J. Brown, Sheboygan, Wisconsin, 

 Septembers, 1890.] 



Reply. — I received this morning from you a box containing a couple of Dragon 

 Flies, which I take to be the species which you have noticed in swarms. An exami- 

 nation shows that it is J^schna eremita Hagen. — [September 11, 1890.] 



On the Oviposition of TacMna. 



The letter of Mr. B. D. Wier in Insect Life, vol. iii, p. 26, contains matter very 

 interesting to me. I was much surprised at the account ot the manner of oviposition 

 of Tachina given by Mr. Webster (vol. ii, p. 256), and was at a loss to account for it, 

 as it differs from published accounts (see A. C. Weeks, Ent. Amer., iii, 126) and from 

 my own experience, but the present letter throws considerable light upon it. The 

 habit of the large parasitic Hymenoptera seems to be to fly up to the larvas at once 

 and attack by a sudden thrust, when the victim usually drops to the ground, as 

 observed by Mr. Wier. Quite in contrast to this is the stealthy approach of the 

 Tachina fly. It will alight near a group of Datana larvae and approach by walking, 

 as it seems to be aware that the noise of its wings would cause alarm. It will 

 approach as nearly as possible to the head of a larva and stealthily deposit one egg 

 after another, the ovipositor passing under the body and out beyond the head. At 

 the slightest movement of its victim the fly will run away and again slowly approach, 

 but is loath to take to flight. I observed this process this season in the case of a 

 number of Datana perspicua, audi also noticed that the Tachina oviposited only upon 

 larvae in their last (fifth) stage, which is an evident protection, as if the eggs were 

 laid upon younger larvae they would often be cast off in molting before they had 

 hatched. 



Mr. Wier seems to think that the larvaj of Datana are not attacked by Tachina on 

 the tree; but I have often observed this, especially in the " hairy form, on the black 

 walnut" (D. inie^emwa), which really appears to be more subject to attack than 

 the ''smooth form" {D. ministra). This double parasitization of integerrima (Mr. 

 Webster's ^* ministra," are probably integerrima as well as Mr. Wier's "hairy form") 

 must result in benefit to it, since both parasites can hardly mature from one larva, 

 but must one or both perish. 



Another fact that I have observed must also tend to check the destruction of Datana 

 by parasites, namely, a protective habit developed by the insects themselves. It con- 

 sists in rubbing the head where Tachina eggs are most usually laid with considerable 

 force on the branch or twig, in many cases serving to dislodge or injure the eggs. 

 That this is a habit, and not due to irritation caused by the presence of eggs, I have 

 proved, by observing that it is freely done by Datana that are not infested and have 

 been bred in the house from the young larvae.' Of course this habit is most marked 

 in the last stage, as this is the time when they are subject to Tachina attack, as I have 

 shown. I have observed the habit in Datana integerrima, ministra, drexelii, major, and 

 perspicua, but not strongly in the last. — [Harrison G- Dyar, Rhinebeck, New York, 

 September 2, 1890. 



Fig Beetles. 



I this day mail you a box containing a half dozen small insects of the kind which 

 destroyed my fig crop last year (1889), and are fast using up my present crop. If you 

 will kindly tell me what they are, and can point out a remedy that promises safety to 

 my figs, I shall be obliged indeed. — [J. M. Fullinwider, Palestine, Texas, August 16, 

 1890. 



Reply. — The small box accompanying your letter contained two species of beetles, 

 known as Carpophilusmutilatus and Epurcea luteola. Both of these beetles confine their 

 attacks to decaying or injured fruit, and will not attack healthy figs. So I think you 

 are mistaken in supposing that they destroy your crop. Please make a closer ex- 

 amination as to the cause of the damage — [August 25, 1890.] 



