I found two yellow spots in the lepidopteran larvae (Tineidae family). They always appear when the larval gut is full of food, whereas In dormant non-feeding larvae, they are invisible. As their color is usually the same with their gut color and they are just visible when the gut is visible, I guess they are part of the excretory or digestive system. I attached photos of different larval stages.
Does anyone know what they are? Are they malpighian tubules or gastric caeca or fat bodies or something else?
To me they appear as testicular buds in their early stage of development. They are not seen in all individuals. Is that so?
Yes, it was. Actually, they were visible in all active feeding individuals. So, they may not be belong to their gender. Do they?
These are definitely the gonades. You can see it both in males and females. The gonades of the male specimens are bigger than the gonades of the females.
Best wishes
Rudolf Ritt
I am certain that they are either a pair of ovaries or testis. To confirm you can dissect the insect and make a temporary slide and then observe under the microscope.
Hi,
In my mind these spots could be a pair of imaginal discs which will be growing at pupate stage. To confirm this, please dissect the larvae before and after feeding and then simply observe them separately under the microscope.
Best wishes
Ali Mehrvar
Thank you all for the answers.
In the case of gonads, is it possible to see both male and female gonads in a species? Or only one of them may be visible in every species?
Why do the spots disappear during dormancy (when their gut is also empty) and then appear again? Are their color related to their nutrition?
You can see both male and female gonads in a species (but of course not both in one specimen!).
I cannot explain why the spots disappear during dormancy or empty gut. Perhaps they are nearer to the surface, when the gut is working?
The colour can change with the gender.
See here: http://www.lepiforum.de/lepiwiki_vgl.pl?Roeslerstammia_Erxlebella
I hope, I could help you!
Best wishes
Rudolf
Hello, I think these two spots are overy or teste. Because the epidermis of this insect is diaphanous.
I agree with most postings above, these structures are gonads due to the position in an abdominal segment as you can compare with the picture on following site: http://lepidoptera.butterflyhouse.com.au/tort/immers.html
Imaginal discs form future appendages of the Imago, and in lepidoptera Imago, I can not figure any appendage of the abdominal segment 5 so far. So it is unlikely to be an imaginal disc.
Dear All,
The yellow spots indicated are gonads of the caterpillar as many of you stressed it. Please have a look at this site http://www.butterflyfunfacts.com/male-female-caterpillar.php
Hello Dear
Many families of moths have special organs to help detect bat echolocation. These organs are known as tympana (singular – typanum). The Pyraloidea and almost all Geometroidea have tympana located on the anterior sternite of the abdomen. The Noctuoidea also have tympana, but in their case, the tympana are located on the underside of the metathorax, the structure and position of which are unique and a taxonomic distinguishing feature of the superfamily
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