445 



nal segment of the male. After fertilization of the female the two 

 continue to fly together and the female is refertilized at intervals 

 during the egg-laying period. At the time of oviposition the two 

 often remain together and the eggs are frequently laid while the pair 

 are still in copula. 



The time elapsing from emergence to egg-laying is not known 

 with any certainty. The egg-laying period also, has been little 

 studied, but it is thought to last for several weeks. 



Food. — Many records have been made of the destruction of mos- 

 quitoes by Anisoptera, but no one seems to have observed or at- 

 tempted to determine the feeding habits of the adults of Zygoptera. 

 Dissection of a number of specimens revealed the fact that the Zy- 

 goptera prefer small Diptera to most other food. Many remains of 

 nematocerous Diptera were found, as the following table will show, 

 but very few remains of other insects. 



Name Food eaten Bate of coll. Locality 



1. Hetaerina americana, g HjTiienoptera (?) Oct. — ,191.5 Muncie, 111. 



2. Ischnura verticalis, g Diptera — abundant re- June 23, 1915 Havana, 111. 



mains 



3. Ischnura verticalis, ^ Alimentary canal empty June 23, 191.5 Havana, 111. 



4. Ischnura verticalis, 5 Many .small Diptera .June 23, 1915 Havana, 111. 



5. Argia apicalis, g Diptera — Nematocera June — , 1915 Clear L., Ky. 



6. EnallagiiM civile, g Diptera June 18, 1915 Ilrbana, 111. 



7. Lestes vigilax, ^ Diptera — Nematocera Bluifton, Ind. 



8. Enallagma hageni, g Diptera — Nematocera July 18, 1915 Orono, Me. 



9. Enallagma antennatum Diptera — Nematocera July 18, 1915 Ilrbana, III. 



10. Ischnura verticalis Large number of butter- July 13, 1915 Lake Villa, 111. 



fly scales 



The most common food of the adult apparently consists of small 

 flies. No remnants were found which resembled mosquitoes, and the 

 hymenopterous insect reported is questionably identified as such. The 

 specimens of lepidopterous scales found in number ten were unmis- 

 takable, and it is, therefore, evident that other insects are sometimes 

 eaten besides Diptera*. They have also been reported to eat aphids. 



Enemies. — The adult Zygoptera are troubled by few enemies of 

 any sort. Birds are perhaps the most important, but even these are 

 not to be considered as serious enemies. Several species of hydrach- 

 nid mites have been found attached to the adult, the most common of 

 which are species of Arrhenurus. The mites are often conspicuous 

 on account of their orange or reddish color, and large numbers often 

 attach themselves to a single individual. However, they seem to 

 cause the insect but little inconvenience. 



*Poulton ('06) reports that both Ephemeridae and Lepidoptera are sometimes 

 eaten. 



